Sequence of Events in the Cockpit on Asiana Flight 214(fearoflanding.com)
fearoflanding.com
Sequence of Events in the Cockpit on Asiana Flight 214
http://fearoflanding.com/accidents/sequence-of-events-in-the-cockpit-on-asiana-flight-214/
10 comments
I thought an absolute rule was that if you are two or more notches below the glideslope (or two notches left or right of the glidepath) on the approach, you must perform a go-around and try again. Maybe this is only for ILS approaches though (this was a visual approach) and maybe this is only a "rule" in quotes and not an actual rule.
In any case the other posts are absolutely correct, monitoring your airspeed on the approach is arguably priority one for a pilot flying an approach. Even if the autopilot is selected and even if airspeed is being controlled by autothrottle, monitoring the airspeed is supposed to be one of the key things to check on the routine "scan" of the instruments as you come in on your approach.
It's inconceivable to me that both the pilot AND the right-hand-seat instructor both missed the drop in airspeed.
Also raising the nose is the wrong thing to do in response to being to low. In fact increasing power (engine thrust) is the thing one is supposed to do in order to increase altitude. Raising the nose is what you do in order to decrease airspeed. It's actually a rookie mistake that beginning private pilots flying single-engine cessnas make. They think throttle = airspeed and elevators (nose up/down) = altitude. The opposite is what you're supposed to do for stable flight.
In any case the other posts are absolutely correct, monitoring your airspeed on the approach is arguably priority one for a pilot flying an approach. Even if the autopilot is selected and even if airspeed is being controlled by autothrottle, monitoring the airspeed is supposed to be one of the key things to check on the routine "scan" of the instruments as you come in on your approach.
It's inconceivable to me that both the pilot AND the right-hand-seat instructor both missed the drop in airspeed.
Also raising the nose is the wrong thing to do in response to being to low. In fact increasing power (engine thrust) is the thing one is supposed to do in order to increase altitude. Raising the nose is what you do in order to decrease airspeed. It's actually a rookie mistake that beginning private pilots flying single-engine cessnas make. They think throttle = airspeed and elevators (nose up/down) = altitude. The opposite is what you're supposed to do for stable flight.
Why do the autopilots/autothrottles control speed by throttle and altitude by elevators, even in aircraft that have AP and AT?
The automated mechanisms use both methods to control the aircraft, depending on the mode they're in. One of the links in the chain of errors that led to the crash of Asiana 214 was that the AP was in the wrong mode for a period of time (during a critical part of the approach).
>So this might be consistent with the information that the captain was transitioning from the Airbus to the Boeing.
>It's a big mystery to me how three pilots could overlook this condition for four minutes.
Three pilots didn't overlook it. One did. Ironically, it was a different Boeing/Airbus distinction that prevented the guy in the left seat of Air France 447 from realizing the mistake the guy in the right seat was making. Airbus has separate (unlinked) controls for both pilots, so the guy in the left seat didn't realize the guy in the right seat was commanding the aircraft to pitch up. In a Boeing, the controls are linked, so it would have been immediately obvious what was happening.
The other pilots were confused because it never occurred to them that someone would try to pitch a staling aircraft 'up'.
>It's a big mystery to me how three pilots could overlook this condition for four minutes.
Three pilots didn't overlook it. One did. Ironically, it was a different Boeing/Airbus distinction that prevented the guy in the left seat of Air France 447 from realizing the mistake the guy in the right seat was making. Airbus has separate (unlinked) controls for both pilots, so the guy in the left seat didn't realize the guy in the right seat was commanding the aircraft to pitch up. In a Boeing, the controls are linked, so it would have been immediately obvious what was happening.
The other pilots were confused because it never occurred to them that someone would try to pitch a staling aircraft 'up'.
Back in the old days of flying (multi engine, no hydraulics) it was typically the right seat that controlled the throttle and hence would have primary responsibility for monitoring the airspeed. So I would say that at least two of the three pilots in the cockpit should have had an eye on the IAS. Also, four red on short always means instant throttle up and evaluate the need for a go around.
They are linked in the Airbus (IIRC it gets the average of the controls if there are two inputs), but the sidestick doesn't provide feedback
Yeah, by 'linked' I meant 'connected by some sort of linkage (ideally physical) that reflects the movements of one controller to the other'
I'm wondering why Airbus adopts this design? Seems very stupid from a cognition point of view. IIRC Air France Flight 447 stalled due to the same issue.
There's a comment down below that explains the reasoning
But the Asiana crash is a Boeing 777
But the Asiana crash is a Boeing 777
Force feedback joysticks are so 2008
Essentially, the rules go like this: white over white: you're too high; red over white, you're just right; red over red, you're dead.
This is drilled into every pilot. Besides, on a visual approach with clear weather, there is absolutely no excuse not to do a go-around if your glideslope is too shallow.
Part of the problem is Airbus aircraft. Similar to how if you write a lot of Python, you slowly forget all of the baggage of C, if you fly with Airbus and the FDC on most of the time, you'll get more used to not having to do more manual work. The sidestick spoils you. Even though the triple-seven is fly-by-wire, there's still a lot less hand-holding in it than the Airbus craft. Same goes for the 787, even though it's a brand-new airplane.
This is drilled into every pilot. Besides, on a visual approach with clear weather, there is absolutely no excuse not to do a go-around if your glideslope is too shallow.
Part of the problem is Airbus aircraft. Similar to how if you write a lot of Python, you slowly forget all of the baggage of C, if you fly with Airbus and the FDC on most of the time, you'll get more used to not having to do more manual work. The sidestick spoils you. Even though the triple-seven is fly-by-wire, there's still a lot less hand-holding in it than the Airbus craft. Same goes for the 787, even though it's a brand-new airplane.
> I guess the biggest question I'm left with after this is how professional pilots can make this kind of elementary piloting mistake: Not watching the airspeed on final approach, and not reacting immediately when the PAPI indicates that the aircraft is too low.
If you know you're prevented from making this mistake on an Airbus, depending on your attention and what you're thinking, you may not remember that the 777 doesn't have the same failsafes.
If you know you're prevented from making this mistake on an Airbus, depending on your attention and what you're thinking, you may not remember that the 777 doesn't have the same failsafes.
There's literally no excuse for not watching your airspeed when you land an airplane, of any make. It's one of the two 'oh-hey-my-life-really-directly-depends-on-this-number' factors.
I really don't like the tone that so many post-accident discussions take regarding automation, Boeing v. Airbus, etc. -- when the plain facts of the incidents (specifically this, and Air France 447) boil down to one small, really important bit willful negligence.
I really don't like the tone that so many post-accident discussions take regarding automation, Boeing v. Airbus, etc. -- when the plain facts of the incidents (specifically this, and Air France 447) boil down to one small, really important bit willful negligence.
I'm sure there are plenty of compensation lawyers, and even pilots, who will agree with you. But from a safety perspective "wilful pilot negligence" simply isn't good enough. In this situation, there just wasn't room for negligence to slip in. If we blame the pilot, we'll miss something important.
A wilfully negligent pilot would be unlikely to get through training. And even if he was sloppy, it's hard to imagine somebody being so negligent that he didn't bother to check his airspeed when landing a 777 under the watchful eye of his instructor. And why didn't the instructor intervene?
Something else is going on. And, yes, if I was a gambling man, I'd put money on the Airbus explanation. I've spoken to Boeing pilots who describe the experience of flying with an Airbus as "creepy" and "eerie". To me, that's a hint that something interesting is happening. I suspect that, by removing certain kinds of feedback, the experience of flying an Airbus is rewiring pilots' brains in dangerous ways.
If I'm right, when we finally get to the bottom of what's going on, we'll learn something important about human cognition and response. This will have important implications for the design of safety critical systems.
This time, it was easy for me to make the case against pilot negligence. It's rarely so clear-cut, and it's normal for people to want to blame the pilot. None more so than the pilots themselves, who love to say, "That couldn't happen to me. I wouldn't make that dumb mistake." This is why the "no-blame culture" is so important in aircraft and medical accident investigations. If we insist on pointing the finger at the human involved, we never learn.
A wilfully negligent pilot would be unlikely to get through training. And even if he was sloppy, it's hard to imagine somebody being so negligent that he didn't bother to check his airspeed when landing a 777 under the watchful eye of his instructor. And why didn't the instructor intervene?
Something else is going on. And, yes, if I was a gambling man, I'd put money on the Airbus explanation. I've spoken to Boeing pilots who describe the experience of flying with an Airbus as "creepy" and "eerie". To me, that's a hint that something interesting is happening. I suspect that, by removing certain kinds of feedback, the experience of flying an Airbus is rewiring pilots' brains in dangerous ways.
If I'm right, when we finally get to the bottom of what's going on, we'll learn something important about human cognition and response. This will have important implications for the design of safety critical systems.
This time, it was easy for me to make the case against pilot negligence. It's rarely so clear-cut, and it's normal for people to want to blame the pilot. None more so than the pilots themselves, who love to say, "That couldn't happen to me. I wouldn't make that dumb mistake." This is why the "no-blame culture" is so important in aircraft and medical accident investigations. If we insist on pointing the finger at the human involved, we never learn.
"I suspect that, by removing certain kinds of feedback, the experience of flying an Airbus is rewiring pilots' brains in dangerous ways."
I don't know whether that's true or not, but that seems something it might be possible for an aircraft design to do, and if so, something to avoid. Does anyone know to what if any extent aircraft designers try to avoid letting pilots become too detached from the experience of flying?
I don't know whether that's true or not, but that seems something it might be possible for an aircraft design to do, and if so, something to avoid. Does anyone know to what if any extent aircraft designers try to avoid letting pilots become too detached from the experience of flying?
I worked on 757 flight controls design back in the early 1980's. I'm not a pilot and I'm not familiar with the Airbus designs.
The 757 flight controls were hydraulically operated, and were controlled by cables operated by the pilot that opened valves on the actuators (hydraulic rams) on the control surfaces. The pilot's controls did not directly feel the flow of air over the control surfaces feeding back into the stick, like a light plane would with the cables moving the control surfaces directly.
To correct this, Boeing designed a "feel computer" that would push back on the controls as if actual wind were pushing on the controls. The idea was that as close as possible the pilot's controls should "feel" like he was directly connected to the control surfaces.
The feel forces generated could be well over a hundred pounds, if I recall correctly, though Boeing had to reduce them in order to accommodate female pilots. Note that for a high performance aerobatic plane with direct controls, it is a physically exhausting task to control it.
My father flew B-17's, which were probably the biggest airplanes without hydraulically assisted controls. You had to be a strong man to fly it. It would fly with only one outboard engine running, but the force required on the rudder pedals meant the pilot and copilot had to constantly relieve each other.
The 757 flight controls were hydraulically operated, and were controlled by cables operated by the pilot that opened valves on the actuators (hydraulic rams) on the control surfaces. The pilot's controls did not directly feel the flow of air over the control surfaces feeding back into the stick, like a light plane would with the cables moving the control surfaces directly.
To correct this, Boeing designed a "feel computer" that would push back on the controls as if actual wind were pushing on the controls. The idea was that as close as possible the pilot's controls should "feel" like he was directly connected to the control surfaces.
The feel forces generated could be well over a hundred pounds, if I recall correctly, though Boeing had to reduce them in order to accommodate female pilots. Note that for a high performance aerobatic plane with direct controls, it is a physically exhausting task to control it.
My father flew B-17's, which were probably the biggest airplanes without hydraulically assisted controls. You had to be a strong man to fly it. It would fly with only one outboard engine running, but the force required on the rudder pedals meant the pilot and copilot had to constantly relieve each other.
There were actually bigger planes, like the Martin JRM Mars (a large WWII flying boat) with a gross takeoff weight in excess of 165,000 lbs. They use a mechanism called a "servo tab," which is sort of like a control surface for the control surface. In essence, it deflects in the opposite direction of the control surface, and usually in proportion to the control force (a system of levers and springs measures the amount of force being transmitted to the controls by the surface).
The primary disadvantage, aside from the complexity of the system, is that it tends to delay feedback, which results in PIO.
The primary disadvantage, aside from the complexity of the system, is that it tends to delay feedback, which results in PIO.
I don't mean that kind of feedback. I mean the feedback you get that teaches you to the limit of the vehicle's operational parameters.
For instance, when I started driving, I sometimes used the brakes too aggressively, and experienced a number of "micro-skids". These experiences quickly taught me how hard I could get away with pushing my vehicle. But it's not something I'm consciously aware of: my foot just automatically reaches for the brake pedal at the right moment. There's a subconscious "anti-skid system" built into my brain.
And that's the way it has to be. I couldn't possibly maintain conscious awareness of all aspects of vehicle operation. I'm not that smart!
The Airbus control scheme takes that feedback away. Pilots don't directly control the plane at all. They merely tell the plane what they want it to do, and the plane's control system decides whether it's a good idea or not. If a pilot does something that would stall the plane, the plane just doesn't respond.
I suspect that this causes the Asiana 214 pilot's subconscious "anti-stall system" to atrophy, to the point where he was no longer competent to manage a Boeing plane. The bit of his brain that automatically monitored flight speed and the red pips was no longer functioning. More seriously, his higher faculties were not aware that his subconscious systems could no longer be trusted (beyond a vague sense of unease).
Well, that's my theory, but note that I haven't explained why the instructor didn't spot what was going on.
For instance, when I started driving, I sometimes used the brakes too aggressively, and experienced a number of "micro-skids". These experiences quickly taught me how hard I could get away with pushing my vehicle. But it's not something I'm consciously aware of: my foot just automatically reaches for the brake pedal at the right moment. There's a subconscious "anti-skid system" built into my brain.
And that's the way it has to be. I couldn't possibly maintain conscious awareness of all aspects of vehicle operation. I'm not that smart!
The Airbus control scheme takes that feedback away. Pilots don't directly control the plane at all. They merely tell the plane what they want it to do, and the plane's control system decides whether it's a good idea or not. If a pilot does something that would stall the plane, the plane just doesn't respond.
I suspect that this causes the Asiana 214 pilot's subconscious "anti-stall system" to atrophy, to the point where he was no longer competent to manage a Boeing plane. The bit of his brain that automatically monitored flight speed and the red pips was no longer functioning. More seriously, his higher faculties were not aware that his subconscious systems could no longer be trusted (beyond a vague sense of unease).
Well, that's my theory, but note that I haven't explained why the instructor didn't spot what was going on.
Well, AFAIK a modern Boeing plane like the 777 / 787 will also prevent stalls just like the Airbus, the difference being that the pilot can override the airplane. So a 777 pilot would also assume that the airplane would normally prevent a stall.
In this accident, I think the main problem was not anything Boeing vs Airbus, but more a lack of experience with hands-on flying visual approaches, and a lack of monitoring, which would quickly have uncovered the fact that the auto-throttle wasn't operating. If the linked PPRune posting has any truth in it, I think we a have a substantial part of the explanation there.
In this accident, I think the main problem was not anything Boeing vs Airbus, but more a lack of experience with hands-on flying visual approaches, and a lack of monitoring, which would quickly have uncovered the fact that the auto-throttle wasn't operating. If the linked PPRune posting has any truth in it, I think we a have a substantial part of the explanation there.
I would say the Airbus comments are incorrect.
Prof. Missy Cummings (former F/A-18 pilot) at MIT is involved in research into cockpit automation. She was featured on at least one documentary into AF447.
What is interesting in the Airbus vs Boeing debate is that pilots like Capt. Sullenberger who has flown both Boeing 737s and Airbus A320s doesn't claim its an "Airbus" problem. The problem is that airline pilots are becoming overly reliant on autopilots and forgetting the basic skills of flying the aircraft. http://www.cbsnews.com/news/capt-sully-sullenberger-airplane...
Prof. Missy Cummings (former F/A-18 pilot) at MIT is involved in research into cockpit automation. She was featured on at least one documentary into AF447.
What is interesting in the Airbus vs Boeing debate is that pilots like Capt. Sullenberger who has flown both Boeing 737s and Airbus A320s doesn't claim its an "Airbus" problem. The problem is that airline pilots are becoming overly reliant on autopilots and forgetting the basic skills of flying the aircraft. http://www.cbsnews.com/news/capt-sully-sullenberger-airplane...
You may be onto something there, but this explanation doesn't cover the instructor, who was experienced on Boeing, not Airbus.
The pilot in question has out and out stated that he was uncomfortable performing visual approaches. Now, while it does indeed boggle the mind as to how such a person could get through training and attain command of a 777, the fact is that he did so. I don't see how you can argue against negligence when the pilot has basically come out and admitted it (although he doesn't seem to think he has).
This reminds me of something (much less substantive and important) that I have been realizing after buying my first Apple computer recently (I held out for a long time). Things like the trackpad and cable wrapping system are so amazingly intuitive, once you figure them out. However, I am so accustomed to sub optimal design, that I had to be shown how to use them both. This may be a case where sub optimal design is a net win, but ensuring that the pilots must stay engaged to at least a minimal degree.
> There's literally no excuse for not watching your airspeed when you land an airplane, of any make.
Completely agree. Unfortunately, the vasty majority of aircraft incidents occur because of pilot error. People can and will make mistakes. We need to accept that or automate more. I'm in the automate more camp.
Completely agree. Unfortunately, the vasty majority of aircraft incidents occur because of pilot error. People can and will make mistakes. We need to accept that or automate more. I'm in the automate more camp.
In the Airbus accident, the level of automation was a contributing factor to the accident. The fly-by-wire system prevents the pilot from placing the aircraft in an unsafe condition. However, this system was automatically deactivated (which is an extremely rare occurence) when the pitot/airspeed tubes were covered with ice and the computer hence couldn't make correctly informed decisions about the aircraft.
In that case, however, you could point to a big UX problem: It was not announced in big, red letters that the fly-by-wire system had in fact been deactivated. If I remember correctly, this was hidden under some menu in the flight computer and simply abstracted away to a "master caution" light or something in that vein.
In that case, however, you could point to a big UX problem: It was not announced in big, red letters that the fly-by-wire system had in fact been deactivated. If I remember correctly, this was hidden under some menu in the flight computer and simply abstracted away to a "master caution" light or something in that vein.
> It was not announced in big, red letters that the fly-by-wire system had in fact been deactivated
It was announced in medium-sized orange letters reading “F/CTL ALTN LAW (PROT LOST)”. At least one pilot did notice this; the co-pilot who wasn’t pulling up the whole time said “alternate law, protections lost” out loud, as recorded on the CVR, when the message appeared.
It was announced in medium-sized orange letters reading “F/CTL ALTN LAW (PROT LOST)”. At least one pilot did notice this; the co-pilot who wasn’t pulling up the whole time said “alternate law, protections lost” out loud, as recorded on the CVR, when the message appeared.
I think he might have noticed, but not fully realized the implications of it. His behaviour following at least did not indicate that he was concerned about a stall, and there were no further mentions of this warning.
Would that not be a UX issue? Perhaps the warning needs to include the phrase "Failsafes deactivated" announced repeatedly.
Yep, I would say that, as far as I remember there were also several other warnings at the same time. There were some recommendations in the accident report regarding UX improvements.
I think there was a similar problems at Qantas Flight 32, where the crew had to spend a lot of time going through 54 error messages after an uncontained engine failure.
I think there was a similar problems at Qantas Flight 32, where the crew had to spend a lot of time going through 54 error messages after an uncontained engine failure.
[deleted]
right, but there was also a pilot who was pulling back on the stick the entire time.
And the airplane averaged the inputs from the two sticks, which strikes me as a positively BRAINDEAD design choice. Why would you ever want to average the two inputs when flying a plane? Are you hoping that one pilot pushing and one pulling will somehow, on average, fly the plane correctly?
The braindead decision (in my uninformed, armchair pilot opinion) was made when the controls were no longer physically linked. Once you have controls that can move independently of each other, none of the options for handling conflicting inputs makes sense to me...
Sum them?
Only take the most extreme of the two inputs (in any given direction)?
Only take the most recently seen input?
Averaging makes more sense than any of those, given the premise of "Control sticks that can move in different directions"
Sum them?
Only take the most extreme of the two inputs (in any given direction)?
Only take the most recently seen input?
Averaging makes more sense than any of those, given the premise of "Control sticks that can move in different directions"
You're right, but I'd go with "the secondary control is ignored and clearly marked as such" ("ignored" light turns on or something). But yeah, if they aren't linked, there's not much you can do that will make sense.
Nah, the right way to compute the final inputs in a case like this is, "This design is stupid and is going to get somebody killed. There is nothing I can do at this level to fix it. You must physically link the two controls."
When assuming that in the normal case the pilots are never doing the opposite of each other ... the difference between each stick is probably less than 5% or something. Agreed that in this case it seems the worst thing to do.
It is rarely discussed, but a major factor contributing to the Airbus crash was that the software did not derive airspeed from engine parameters and use it to verify the pitot tubes. The common mode failure of the pitot tubes could have been anticipated and protected against.
The problem there being when something unexpected happens that the automation can't cope with, your skills have atrophied.
I'm not a pilot but I am a technical diver, and we eschew many of the conveniences that recreational divers use, such as relying on dive computers. We work out dive plans on paper, and backup plans, and carry them with us on a slate. The only instruments we rely on are watch, depth gauge and compass, and these are of the simplest possible design, and we have backups for them. If something happens on a deep dive or a cave dive, you know exactly what the state of your system is and can reason about it. Not so if you were used to something else tracking it for you, and you had to start discovering it from scratch.
I'm not a pilot but I am a technical diver, and we eschew many of the conveniences that recreational divers use, such as relying on dive computers. We work out dive plans on paper, and backup plans, and carry them with us on a slate. The only instruments we rely on are watch, depth gauge and compass, and these are of the simplest possible design, and we have backups for them. If something happens on a deep dive or a cave dive, you know exactly what the state of your system is and can reason about it. Not so if you were used to something else tracking it for you, and you had to start discovering it from scratch.
While mistakes in aggregate are inevitable, individual mistakes are not, and neither are certain categories of mistakes.
Not paying attention to your airspeed is the sort of mistake you should be able to eradicate.
I want to know why a pilot who says that he is "very concerned" with doing a simple visual approach is allowed to have a couple hundred lives in his hands in an airliner. This is Piloting 101.
Mistakes are inevitable, but we shouldn't just throw up our hands either, especially when this particular mistake comes down to straight-out incompetence and a pilot who's afraid of a basic and straightforward flight operation.
Not paying attention to your airspeed is the sort of mistake you should be able to eradicate.
I want to know why a pilot who says that he is "very concerned" with doing a simple visual approach is allowed to have a couple hundred lives in his hands in an airliner. This is Piloting 101.
Mistakes are inevitable, but we shouldn't just throw up our hands either, especially when this particular mistake comes down to straight-out incompetence and a pilot who's afraid of a basic and straightforward flight operation.
You keep reading an awful lot into a single line, taken from an interview after the accident, possibly with translation and/or language barrier, without even knowing how the question was phrased.
Would you feel better if he said he was "not concerned at all" with landing the airplane?
Would you feel better if he said he was "not concerned at all" with landing the airplane?
I'm using that single line as a summary, not the sole evidence.
> [The pilot] "stated it was very difficult to perform a visual approach with a heavy airplane."
From http://www.cbsnews.com/news/ntsb-asiana-crash-pilot-very-con...
This is, of course, complete bullshit.
From the same article:
> Lee said he told his instructors about his concerns in the flight's planning stages. He told investigators that as he realized his approach was off, he was worried he might "fail his flight and would be embarrassed."
More:
> Since “everyone else had been doing the visual approach … he could not say he could not do the visual approach,” according to NTSB
From http://atwonline.com/safety/asiana-777-pilot-sfo-visual-appr...
Would I feel better if he said he was "not concerned at all"? Of course I would. He was performing an easy landing in completely benign weather at an airport with nothing at all tricky or unusual about its approach. There was no reason whatsoever to be concerned.
> [The pilot] "stated it was very difficult to perform a visual approach with a heavy airplane."
From http://www.cbsnews.com/news/ntsb-asiana-crash-pilot-very-con...
This is, of course, complete bullshit.
From the same article:
> Lee said he told his instructors about his concerns in the flight's planning stages. He told investigators that as he realized his approach was off, he was worried he might "fail his flight and would be embarrassed."
More:
> Since “everyone else had been doing the visual approach … he could not say he could not do the visual approach,” according to NTSB
From http://atwonline.com/safety/asiana-777-pilot-sfo-visual-appr...
Would I feel better if he said he was "not concerned at all"? Of course I would. He was performing an easy landing in completely benign weather at an airport with nothing at all tricky or unusual about its approach. There was no reason whatsoever to be concerned.
Yep, and this is backed up by all the other airplanes taking off and landing visually that same day without any issues.
I think the main problem is the more automation still has to be accompanied with more training of the pilots, up until we have a situationally aware computer that can consistently make better decisions than their human counterparts. For safety critical aviation software, I think we are a few decades away from that.
[deleted]
I don't hold ATP though I believe it is irrelevant here... Basically they lost situational awareness and got behind the plane: they didn't understand what is going on with the plane systems (autopilot) and failed to "fly the plane". While the NTSB report doesn't state this, I would not be surprised to learn that they actually didn't look outside of the window and instead they were head down punching buttons to reprogram the system. I'll speculate that the whole accident became possible due to the lack of VFR flying by Asiana pilots that a typical US pilot gets way before s/he gets into the airliner.
Airline pilot here with experience in B737, MD 80 and Airbus A320, so I know the flight controls philosophy of each one and the main differences.
-First of all, it is what it seems, it´s an elementary piloting failure. Once you disconnect the Autopilot and/or auto-throttle you must be first of all flying the plane on it´s envelope then navigating and last combating an emergency (if there is one).
-Second, I´ve heard first hand how the basic piloting skills like a visual approach or manual flying are very scarce in several Asian countries, one of them is Korean. This is due to the initial and airline training philosophy, for example Chinese copilots are not allowed to take the controls for landing or take off EVER (they have eternal training periods that are useless as they have no skills at all to learn ) I´dont know if this is true for all companies but at least several big ones work like this. Opposite to this in European and American companies, flight officers do half of the take off and landings due for the day, the only difference between a captain and copilot is that the captain is the one who decides the big questions, but the copilot is required to have the same piloting skills. In this case they were two captains one of them an instructor.. No words.
-third, there is an American instructor who wrote at Pprune (a pilot forum) about how for Korean pilots (trained in Korea), the worst emergency they can suffer in a simulator is a visual approach. Even worst than losing both engines or total hydraulic failure. They are scared to death of visual flying. . He was fired from Asiana for failing to pass the annual exam to one of Asiana´s top pilots for failing a common visual approach. It seems that due to the problems with North K. it´s not possible to flight small airplanes and practice the basic skills. I can not find the article right now, I think it was erased shortly after being posted.
-Fourth, it´s common to do mistakes with the flight modes while on final approach, both with airbus and Boeing, there are several descend and ascend modes, speed modes, and auto-throttle modes. But basically is that if you are high you want to descend faster, if you are low, you want to reduce your descend or even climb (in case of obstacles ahead), and you want to keep your speed inside the restricted limits needed to flight with the flaps for landing (too fast and they bend, too slow and you crash). When a mistake happens is normal to disconnect the autopilot and/or auto-throttle and take over on manual. But of course you are aware of what´s happening, is like going with the cruise control on the car, disconnecting it and failing to brake at the next light.
-Fifth, there are differences between airbus and Boeing, an airbus would have done an automatic full throttle to recover the low speed. But this kind of automatic behavior has other costs, for example the Air France´s A330 that crashed in my opinion was due to an overconfidence in such automatic recover. The problem (and this is my opinion) is that the pilot flying thought that just pulling the stick the airplane would do the rest to recover whatever he thought was happening ( Once it was in to a deep stall, it was impossible for the computer to recognize what was happening).
I think that crashing in crystal clear weather on a big airport just because you don´t know how to flight manually is a problem that some companies and countries have with the flight instruction philosophy, no amount of technology is going to solve that. Now Airbus is trying to increase the manual training of the pilots just because this same reason. They just went too far automatizing the flight, but airplanes and computers fail, and when they do it while flying you just can not stop everything to solve the problem, you have to land the plane safely no matter what.
-First of all, it is what it seems, it´s an elementary piloting failure. Once you disconnect the Autopilot and/or auto-throttle you must be first of all flying the plane on it´s envelope then navigating and last combating an emergency (if there is one).
-Second, I´ve heard first hand how the basic piloting skills like a visual approach or manual flying are very scarce in several Asian countries, one of them is Korean. This is due to the initial and airline training philosophy, for example Chinese copilots are not allowed to take the controls for landing or take off EVER (they have eternal training periods that are useless as they have no skills at all to learn ) I´dont know if this is true for all companies but at least several big ones work like this. Opposite to this in European and American companies, flight officers do half of the take off and landings due for the day, the only difference between a captain and copilot is that the captain is the one who decides the big questions, but the copilot is required to have the same piloting skills. In this case they were two captains one of them an instructor.. No words.
-third, there is an American instructor who wrote at Pprune (a pilot forum) about how for Korean pilots (trained in Korea), the worst emergency they can suffer in a simulator is a visual approach. Even worst than losing both engines or total hydraulic failure. They are scared to death of visual flying. . He was fired from Asiana for failing to pass the annual exam to one of Asiana´s top pilots for failing a common visual approach. It seems that due to the problems with North K. it´s not possible to flight small airplanes and practice the basic skills. I can not find the article right now, I think it was erased shortly after being posted.
-Fourth, it´s common to do mistakes with the flight modes while on final approach, both with airbus and Boeing, there are several descend and ascend modes, speed modes, and auto-throttle modes. But basically is that if you are high you want to descend faster, if you are low, you want to reduce your descend or even climb (in case of obstacles ahead), and you want to keep your speed inside the restricted limits needed to flight with the flaps for landing (too fast and they bend, too slow and you crash). When a mistake happens is normal to disconnect the autopilot and/or auto-throttle and take over on manual. But of course you are aware of what´s happening, is like going with the cruise control on the car, disconnecting it and failing to brake at the next light.
-Fifth, there are differences between airbus and Boeing, an airbus would have done an automatic full throttle to recover the low speed. But this kind of automatic behavior has other costs, for example the Air France´s A330 that crashed in my opinion was due to an overconfidence in such automatic recover. The problem (and this is my opinion) is that the pilot flying thought that just pulling the stick the airplane would do the rest to recover whatever he thought was happening ( Once it was in to a deep stall, it was impossible for the computer to recognize what was happening).
I think that crashing in crystal clear weather on a big airport just because you don´t know how to flight manually is a problem that some companies and countries have with the flight instruction philosophy, no amount of technology is going to solve that. Now Airbus is trying to increase the manual training of the pilots just because this same reason. They just went too far automatizing the flight, but airplanes and computers fail, and when they do it while flying you just can not stop everything to solve the problem, you have to land the plane safely no matter what.
-third, there is an American instructor who wrote at Pprune (a pilot forum) about how for Korean pilots (trained in Korea), the worst emergency they can suffer in a simulator is a visual approach ... I can not find the article right now, I think it was erased shortly after being posted.
Here's a reprint. It's very interesting: http://www.freerepublic.com/focus/f-news/3041469/posts
Here's a reprint. It's very interesting: http://www.freerepublic.com/focus/f-news/3041469/posts
> The Koreans are very very bright and smart so I was puzzled by their inability to fly an airplane well. They would show up on Day 1 of training (an hour before the scheduled briefing time, in a 3-piece suit, and shined shoes) with the entire contents of the FCOM and Flight Manual totally memorized. But, putting that information to actual use was many times impossible. Crosswind landings are also an unsolvable puzzle for most of them. I never did figure it out completely, but I think I did uncover a few clues. Here is my best guess. First off, their educational system emphasizes ROTE memorization from the first day of school as little kids. As you know, that is the lowest form of learning and they act like robots. They are also taught to NEVER challenge authority and in spite of the flight training heavily emphasizing CRM/CLR, it still exists either on the surface or very subtly. You just cant change 3000 years of culture.
I've experienced this throughout my professional career as an engineer, to the point where I am very reluctant to work with foreign born asians. I find that this trait is very cultural, as it is almost completely absent in asians that were born in the US.
I've experienced this throughout my professional career as an engineer, to the point where I am very reluctant to work with foreign born asians. I find that this trait is very cultural, as it is almost completely absent in asians that were born in the US.
holy crap that article scared the crap out of me, if what he says is true, I am not flying with pilots out of Korean flight school. What he says about the culture of rote memorization and lack of outside box thinking holds some merit before we all cry about how this has nothing to do with East Asian culture. I don't give a damn about culture but if it's preventing you from being able to pass a flying simulation test that is standard, it pretty much makes me NOT want to fly with that airline.
I don't care if American airlines offer crappy inflight customer service compared to Asiana airlines, I DEMAND a pilot that have the qualification to fly and land the airplane in all possible scenarios. If Asiana pilots can't even pass the flight sims, no way in hell I'm letting them fly the plane.
I'm just so angry after reading the article. How fucking hard can it be? I played Microsoft Flight Simulator since 4.5 since the DOS version. Of course the flight simulation is more difficult than a simulator on the computer but I am trying to illustrate how ridiculous the Korean pilots attitude is. It's like they treat it as some demeaning labor (Korean society judges a person a lot by their occupation if it's not a traditionally Confucius approved position like scholar, professor, lawyer, doctor, prosecutor). You are responsible for hundreds of peoples lives and you can't even land the fucking plane on a flight simulator via visual approach because you are afraid of screwing up or looking bad in front of your superior officer? You can't even say that the emperor is naked because someone above you says he isn't?
And why the hell did that Korean American pilot for Asiana or KAL get arrested and JAILED, for starting a union? Was he suspected of being a communist for wanting to be paid by the flight hour time?
I don't care if American airlines offer crappy inflight customer service compared to Asiana airlines, I DEMAND a pilot that have the qualification to fly and land the airplane in all possible scenarios. If Asiana pilots can't even pass the flight sims, no way in hell I'm letting them fly the plane.
I'm just so angry after reading the article. How fucking hard can it be? I played Microsoft Flight Simulator since 4.5 since the DOS version. Of course the flight simulation is more difficult than a simulator on the computer but I am trying to illustrate how ridiculous the Korean pilots attitude is. It's like they treat it as some demeaning labor (Korean society judges a person a lot by their occupation if it's not a traditionally Confucius approved position like scholar, professor, lawyer, doctor, prosecutor). You are responsible for hundreds of peoples lives and you can't even land the fucking plane on a flight simulator via visual approach because you are afraid of screwing up or looking bad in front of your superior officer? You can't even say that the emperor is naked because someone above you says he isn't?
And why the hell did that Korean American pilot for Asiana or KAL get arrested and JAILED, for starting a union? Was he suspected of being a communist for wanting to be paid by the flight hour time?
When a mistake happens is normal to disconnect the autopilot and/or auto-throttle and take over on manual.
Is the mistake that they made here that they used the flight level change mode for final approach where they shouldn't have done that to begin with? Or what is the mistake they made they caused them to turn off autopilot?
My second question is the one I originally had when reading the article:
The pilot flying responded by disconnecting the autopilot and manually retarding the throttles to idle. In this configuration, the autopilot was not commanding the airplane, although the system made inputs to the flight directors because it was still in flight level change mode.
I don't understand this. What does it mean to turn off autopilot but still have the plane give input due to the AP mode? Is what the article saying that the pilot simply turned off the AP voice warnings but left the AP input on? - if so, I don't understand why that should even be possible.
What are the scenarios where you would want to leave the AP inputs on but switch off the audio warnings other than the pilot "finding them annoying" (!!) ?
Is the mistake that they made here that they used the flight level change mode for final approach where they shouldn't have done that to begin with? Or what is the mistake they made they caused them to turn off autopilot?
My second question is the one I originally had when reading the article:
The pilot flying responded by disconnecting the autopilot and manually retarding the throttles to idle. In this configuration, the autopilot was not commanding the airplane, although the system made inputs to the flight directors because it was still in flight level change mode.
I don't understand this. What does it mean to turn off autopilot but still have the plane give input due to the AP mode? Is what the article saying that the pilot simply turned off the AP voice warnings but left the AP input on? - if so, I don't understand why that should even be possible.
What are the scenarios where you would want to leave the AP inputs on but switch off the audio warnings other than the pilot "finding them annoying" (!!) ?
They were flying with vertical speed, with that mode you tell exactly to the AP how fast you want to go up or down( 1000ft/min is anormal rate for approach). For that mode you don't need a lower capture altitude selected if you are descending (or the opossite if you are climbing). So they set the go around altitude on the selector, this is done to be prepared in case of a go around and the altitude is given by the standart approach procedure you are performing.
So they are descending but the altitude selected is higher than them. Till this point there is nothing unusuall if you are flying a visual approach. Then they realize they are descending too slowly and they are high on the approach. This is not unusual nor dangerous. To loose that excess altitude they select the descend mode "Level Change", this means that the plane is going to capture the selected altitude, if it's higher it will apply power and climb, if it's lower it will set the engines to iddle and descend.
As they had selected a higher altitude the plane set climb power and rised the attitude to climb. Not even this moment is dangerous, as I said it happens sometimes. They disconnected the autopilot and autothrottle and begun to descend manually. As they had excess altitude the speed is was not a problem initially you change altitude for speed, and descend at a faster rate to reach the ideal glide slope. All this is a quite usuall procedure that we perform quite often when high on the glide.
Their mistake was that once they reached the desired visual glide path from above you need to apply a bit of power (around 50%N1 ) to reduce the descend and keep the speed. They correctly pulled the nose to follow the glide but forgot to apply power. Then the speed started to decrease slowly till it went too far down and they stalled into the ground.
The reply to the second question is that they disconnected the autopilot and autothrottle, but the flight director was still on and trying to go up. The flight director are two bars located at the center of the artificial horizont that tell you were you need to put the airplane symbol to flight the selected path. It helps quite a lot, because manual flying inside the clouds requires a lot of concentration on the basic positions of the artificial horizont,speed and heading. The flight director makes it much easier so you can concentrate in other tasks.
It's recommended that when you are flying visually and ignoring the flight director, to disconnect it so it doesnt give you misleading indications. This happened to them, they were descending but the FD was telling them to climb (as it had been selected eith level change). This maybe disconcerted them when they reached te visual glide. But the biggest problem was their failure to apply power manuallyto the thrust levers.
Sorry for the wall of text, but I'm writing from my Iphon and I can't make the intro work and separate the text in paragraphs.
I read on pprune earlier this year that the instructor who had the most hours on the 777 was junior in rank to the pilot transitioning, and due to the way Korean society is regarding rank, might not have wanted to overrule a "senior" officer.
Sounds unlikely in this day and age, but 20 years ago other air crashes from Korean airlines were apparently due to the same thing with junior pilots not wanting to overrule or speak up against a senior pilot who had made a mistake or overlooked something, so who knows...
Sounds unlikely in this day and age, but 20 years ago other air crashes from Korean airlines were apparently due to the same thing with junior pilots not wanting to overrule or speak up against a senior pilot who had made a mistake or overlooked something, so who knows...
Would it be practical to institute a rule that once a pilot has flown an Airbus they can't commercially fly a Boeing?..
I could see the Airbus lobby pushing heavily for something like this :)
That would not be practical or necessary. What is necessary (and is being worked on after AF447) is giving pilots more hands-on flying experience. This is a concern not only for Airbus pilots, but for Boeing pilots as well.
As an aside to my question above.
Do pilots transitioning from the Airbus to the Boeing get put through an intensive simulator training to '(re)acclimatise' them to the Boeing.
By intensive I mean going through a whole host of failure modes.
Do pilots transitioning from the Airbus to the Boeing get put through an intensive simulator training to '(re)acclimatise' them to the Boeing.
By intensive I mean going through a whole host of failure modes.
Yes. Each new airplane type that you're going to pilot requires you to first attain a Type Rating[1] in it.
For instance, I picked a random link to a flight school that offers a B777 type rating course[2] - which takes 14 days of ground-work and 9 days of flight training (36 hours in the simulator in this case; often for big airliners it's going to be too expensive or impractical to perform a type-rating in a real aircraft).
Additionally, having attained the type rating, you're required to maintain "currency" in that type by flying it frequently; if you let type currency lapse by going too long without flying it, you need to undergo a kind of mini "refresher" training/assessment to regain currency again. This is the case for Private/GA Pilots in NZ at least, I'm not so familiar with other jurisdictions or license categories.
[1] http://en.wikipedia.org/wiki/Type_rating
[2] http://www.balticaa.com/en/aviation-training-courses-/type-r...
For instance, I picked a random link to a flight school that offers a B777 type rating course[2] - which takes 14 days of ground-work and 9 days of flight training (36 hours in the simulator in this case; often for big airliners it's going to be too expensive or impractical to perform a type-rating in a real aircraft).
Additionally, having attained the type rating, you're required to maintain "currency" in that type by flying it frequently; if you let type currency lapse by going too long without flying it, you need to undergo a kind of mini "refresher" training/assessment to regain currency again. This is the case for Private/GA Pilots in NZ at least, I'm not so familiar with other jurisdictions or license categories.
[1] http://en.wikipedia.org/wiki/Type_rating
[2] http://www.balticaa.com/en/aviation-training-courses-/type-r...
I think that a flight path vector (velocity vector) would be really useful in this case. I don't know whether B777's PFD has it, though.
Honestly, the altitude and airspeed indicators provide a completly suitable situational awareness in cases like this.
I agree; however, the Air France incident you are referring to is when the airspeed indicator was locked due to a frozen pitot tube, wasn't it? That seems like a much less blatant failure on the part of the pilots.
You may have already read this, but if not, this is an incredibly chilling reconstruction of the events leading up to that crash:
http://www.popularmechanics.com/technology/aviation/crashes/...
Key excerpt from halfway through:
"Another of the pitot tubes begins to function once more. The cockpit's avionics are now all functioning normally. The flight crew has all the information that they need to fly safely, and all the systems are fully functional. The problems that occur from this point forward are entirely due to human error."
Really tragic.
http://www.popularmechanics.com/technology/aviation/crashes/...
Key excerpt from halfway through:
"Another of the pitot tubes begins to function once more. The cockpit's avionics are now all functioning normally. The flight crew has all the information that they need to fly safely, and all the systems are fully functional. The problems that occur from this point forward are entirely due to human error."
Really tragic.
Right, but how does the cockpit crew know that they airspeed indicators are working correctly now? They don't.
Popular Mechanics did a mesmerizing writeup of the Air France transcript. Worth a read:
http://www.popularmechanics.com/technology/aviation/crashes/...
http://www.popularmechanics.com/technology/aviation/crashes/...
Read the report. The pitot tubes thawed after about one minute. Everything after was pilot error. After the high-altitutde stall, the pilot-in-control kept the angle of attack above 30 degrees.
All pilots are trained to recognize issues like a frozen pitot tube and there is a very simple solution - activate pitot heat and maintain level flight using your attitude indicator until your airspeed indicator starts working again.
The pilot depended on automation to fly the plane. When put into a situation where it was not available, he crashed it showing insufficient piloting skill. That someone with this lack of skill was placed in this situation shows institutional failure.
Agreed. I can't fathom how a person who self-described as "very concerned" with doing a visual approach got into the cockpit of a 777. That's the sort of thing I'd expect from a fresh student pilot who spent too much time playing with the ILS in his flight simulator.
Alright, but how do you explain the instructor who had 3,200 hours on the 777 who was sitting beside the pilot not making any mention of a too low airspeed or incorrect landing configuration right up until it was to late? Makes me wonder if there was some ambiguity in the instrument display or procedures for neither pilot to make mention of any problems.
The pilot expressed his concerns about performing a visual approach to his instructor before the flight. The instructor let him fly anyway instead of instantaneously grounding him and saying, "WTF? This is Piloting 101, go get your shit together."
The instructor let this person fly when he was lacking such a basic skill, and that the instructor came from the same system that allowed this incompetent pilot to attain command of a large airliner. This to me indicates that the system is broken and there's no reason to think it couldn't produce an instructor who was also completely useless at performing a visual approach.
The instructor let this person fly when he was lacking such a basic skill, and that the instructor came from the same system that allowed this incompetent pilot to attain command of a large airliner. This to me indicates that the system is broken and there's no reason to think it couldn't produce an instructor who was also completely useless at performing a visual approach.
maybe if he had been playing more with his flight sim this wouldn't have happened. it's such a basic mistake to make.
Exactly
The weather was as good as it gets. Anyone that had experience with "landing a plane", not pressing buttons like the modern cockpits encourage you to do would have landed it safely.
There have been some complaints about pilots from Korea (of course, not only them, but there are some structural problems in Korea that help this) not having good manual flight experience.
The weather was as good as it gets. Anyone that had experience with "landing a plane", not pressing buttons like the modern cockpits encourage you to do would have landed it safely.
There have been some complaints about pilots from Korea (of course, not only them, but there are some structural problems in Korea that help this) not having good manual flight experience.
I've spent time conducting basic flight training for international students (including Korean) and am now an airline pilot. Though I don't have much experience with international operations, what I saw as an instructor is freshly minted pilots going back to their home countries and immediately being put into the right seat of an airliner. Many of these students were very poor pilots, however, as long as they have the money, the flight training machine that exists in states like Florida will keep training them, and international airlines will continue to hire the product. It's a matter of national pride for many countries to be able to employ their own citizens as pilots. Many will cease learning as soon as they leave flight school due to the poor training environments that exist in some places.
Going from a small prop plane to an airliner is perfectly acceptable. It's been going on for a long time and can produce safe pilots, but those pilots need to understand basic stick and rudder flying and continue to hone their skills. Unfortunately, many get started using the automation and allow their flying skills to atrophy. This is true for long-time airline pilots as well.
In the US, by the time a pilot has reached the cockpit of something like a 777, they've gained quite a bit of experience flying smaller prop planes and regional jets, which require a little more work on the part of the pilot. The visual approach assigned to Asiana Flight 214 is a non-issue to US airlines. It's a routine, every day occurrence that doesn't cause one to become "very concerned", however, many countries choose to focus their pilot training more on managing automation than flying the aircraft, and I think that cultural difference played a big part in this crash.
Talk to a US airline pilot who has worked with a training department internationally. The stories you'll hear are pretty eye opening.
Going from a small prop plane to an airliner is perfectly acceptable. It's been going on for a long time and can produce safe pilots, but those pilots need to understand basic stick and rudder flying and continue to hone their skills. Unfortunately, many get started using the automation and allow their flying skills to atrophy. This is true for long-time airline pilots as well.
In the US, by the time a pilot has reached the cockpit of something like a 777, they've gained quite a bit of experience flying smaller prop planes and regional jets, which require a little more work on the part of the pilot. The visual approach assigned to Asiana Flight 214 is a non-issue to US airlines. It's a routine, every day occurrence that doesn't cause one to become "very concerned", however, many countries choose to focus their pilot training more on managing automation than flying the aircraft, and I think that cultural difference played a big part in this crash.
Talk to a US airline pilot who has worked with a training department internationally. The stories you'll hear are pretty eye opening.
Good article. In the US and some other places around the world, you'll find pilots who are equally capable of flying automated Airbus type aircraft as they are 1960's style cockpits using old fashioned radio navigational aids. I take pride in my skills and ability to operate an aircraft safely. Unfortunately, what I know seems to be becoming a lost art, and the state of the piloting profession internationally will likely speed the process of automating pilots out of the cockpit. It's sad, and I've become pretty keen on learning a new skill in preparation for the demise of my job.
If you found this article interesting you might also want to read Normal Accidents http://en.wikipedia.org/wiki/Normal_Accidents which details many similar accidents in planes, ships, nuclear power plants, and more. The author proposes a model for identifying complex, tightly coupled systems in which operators have little chance of avoiding error. The parallels to operational failure in complex, tightly coupled software are evident (at least they seem so to me).
"captain @, @ had too much herb medicine and his liver numbers are too high"
and then
"It's absurd it works at Air Busan, but not in my company"
Note to self, never flying Air Busan.
and then
"It's absurd it works at Air Busan, but not in my company"
Note to self, never flying Air Busan.
"Due to the potentially disturbing nature of the surveillance video we are about to show, we will pause for a moment to let [people?] exit the room if they choose." (9:22)
Is it the standard warning for these hearings?
Is it the standard warning for these hearings?
I assume family could be present?
The insistence of aviation and naval industries to continue using knots for speeds is infuriating.
I can forgive the fact that the article uses U.S. customary units instead of SI but the article gives distances in miles and altitudes in feet and needing to convert knots into feet per second or miles per hour as you read is awful.
I can forgive the fact that the article uses U.S. customary units instead of SI but the article gives distances in miles and altitudes in feet and needing to convert knots into feet per second or miles per hour as you read is awful.
The knot is now defined in terms of an SI unit (1 knot = 1 nautical mile/hour, 1 nautical mile = 1852 meters), and the nautical mile is accepted for use internationally by BIPM.
Its continued use is due to the fact that the nautical mile is the average length of one minute of arc along a meridian, which allows easy correction, when measuring distances in nautical miles, for the distortions of representing the non-flat Earth on flat charts.
Or, more simply: there are sometimes good reasons for using a unit other than "look how easy it is to move decimal points".
Its continued use is due to the fact that the nautical mile is the average length of one minute of arc along a meridian, which allows easy correction, when measuring distances in nautical miles, for the distortions of representing the non-flat Earth on flat charts.
Or, more simply: there are sometimes good reasons for using a unit other than "look how easy it is to move decimal points".
Or to put it another way: a nautical mile is equal to one minute of latitude and 60 nautical miles equals one degree of latitude.
I've seen many people become amazed when it's explained to them that a nautical mile is not just an archaic, arbitrary unit of measure, like a hogshead or furlong. Part Two of this explanation is to tell them that the metric system unit of distance, the meter, was also originally based on the earth's size. Ten million meters (or 10,000 km) is the distance from the equator to one of the poles.
I've seen many people become amazed when it's explained to them that a nautical mile is not just an archaic, arbitrary unit of measure, like a hogshead or furlong. Part Two of this explanation is to tell them that the metric system unit of distance, the meter, was also originally based on the earth's size. Ten million meters (or 10,000 km) is the distance from the equator to one of the poles.
Yes it turns out practitioners in the field prefer a convention that makes their jobs easier and not one for the convenience of The Internets. Who'da thunk it?
I can imagine someone saying programmers are stupid for insisting that k means 1024 instead of 1000 like, umm, SI units...
I can imagine someone saying programmers are stupid for insisting that k means 1024 instead of 1000 like, umm, SI units...
from Wikipedia:
> The speeds of vessels relative to the fluids in which they travel (boat speeds and air speeds) are measured in knots.
It's a little like the difference between mass and weight - the frame of reference is important for one and not the other.
> The speeds of vessels relative to the fluids in which they travel (boat speeds and air speeds) are measured in knots.
It's a little like the difference between mass and weight - the frame of reference is important for one and not the other.
[deleted]
The absolute quantities rarely matter. 100 knots in a 777 is completely different from 100 knots in a Cessna 150. The units are not too terribly important, since the reference numbers you're comparing them to are always in the same units.
The pilots attempted to go around at the last second, when it was already too late - if the pilots had not attempted to go around, i.e. not piled on the throttle at the last second - just wondering - would the crash have been as severe?
It would have been worse^. Throttle response is far from instantaneous (jets spool relatively slowly), and any speed that they did manage to gain contributed greatly to lift and almost certainly lessened the force of the impact.
Throttling up a plane for a go around is not at all analogous to stepping on the gas while crashing into a brick wall.
^ total speculation
Throttling up a plane for a go around is not at all analogous to stepping on the gas while crashing into a brick wall.
^ total speculation
They made the runway, it's how they were able to interview the pilots. If they hadn't done anything, I'd expect more of the plane would have hit the seawall instead of just the tail gear. It probably would have been much worse.
Forgive me if I'm a little behind, but is the official consensus that this was a human error? That the measurements were presented correctly to the crew and that a veteran pilot wouldn't have made these mistakes?
To the best of my knowledge, the NTSB has not released any preliminary assignment of blame. They spend years on these sort of things, checking every detail, dotting every 'i' and crossing every 't' before they make those determinations, as they carry a huge amount of weight. (And I do think this is the appropriate thing to do).
That being said, from all the information that is publicly available, the consensus of everyone else seems to be that it is human error, as there have been no reports of any of the plane's systems not performing normally given the inputs of the crew.
Now, that being said, we shouldn't say "Pilot Error" and move on, but should instead look for any systematic flaws that allowed the pilot error to take place. This might be the result of training issues, or the airlines policies on crew rest, or something else that we can remediate to prevent this sort of thing from recurring in the future
That being said, from all the information that is publicly available, the consensus of everyone else seems to be that it is human error, as there have been no reports of any of the plane's systems not performing normally given the inputs of the crew.
Now, that being said, we shouldn't say "Pilot Error" and move on, but should instead look for any systematic flaws that allowed the pilot error to take place. This might be the result of training issues, or the airlines policies on crew rest, or something else that we can remediate to prevent this sort of thing from recurring in the future
I don't know if it's the consensus, but that's certainly how it looks to me (PPIASEL - private pilot instrument airplane single engine land). Complete and utter incompetence. The Koreans are actually notorious for this.
http://blog.rongarret.info/2013/07/do-not-fly-asiana-or-kal....
http://blog.rongarret.info/2013/07/do-not-fly-asiana-or-kal....
wow, stereotype much?
Why do you glibly dismiss it as a "stereotype"? Did you read the post that prompted him to write that? It was preserved on HN:
https://news.ycombinator.com/item?id=6025525
That post discusses in detail exactly what is wrong with the training culture in Korea. Do you have any knowledge or experience to dispute the post? Can you come up with something more enlightening than the 3 word reply "wow, stereotype much?"?
BTW this criticism of flying culture in many foreign airlines isn't just found in this one post. Read pprune.org and you will find many many similar stories. Are all those people posting simply making things up?
I don't think so.
That post discusses in detail exactly what is wrong with the training culture in Korea. Do you have any knowledge or experience to dispute the post? Can you come up with something more enlightening than the 3 word reply "wow, stereotype much?"?
BTW this criticism of flying culture in many foreign airlines isn't just found in this one post. Read pprune.org and you will find many many similar stories. Are all those people posting simply making things up?
I don't think so.
And this post demolishes Gladwell's theory rather thoroughly.
http://askakorean.blogspot.com.au/2013/07/culturalism-gladwe...
http://askakorean.blogspot.com.au/2013/07/culturalism-gladwe...
So what? Just because some author advanced a flawed argument does not change the fact that Koreans account for a greater share of aircraft accidents caused by pilot error than could be reasonably accounted for by random chance. Just because an argument is flawed doesn't mean the conclusion is false.
The link I posted notes that 3 of the 7 crashes where Gladwell blames "pilot error" were actually caused by being shot down by the Soviets (x2) and being bombed by the North Koreans (x1). Which pretty much removes the statistical anomaly of Korean airlines having more accidents.
Look, we all agree that Malcolm Gladwell is an idiot, so the fact that he cites bogus data contributes nothing to the discussion. Happily, we don't need to rely on Gladwell's data. Korean air lines have had so many incidents and accidents that there's a whole wikipedia page about them:
http://en.wikipedia.org/wiki/Korean_Air_incidents_and_accide...
"Korean Air had many fatal accidents between 1970 and 1999, during which time it wrote off 16 aircraft in serious incidents and accidents with the loss of 700 lives. The last fatal accident, Korean Air Cargo Flight 8509 in December 1999 led to a review of how Korean cultural attitudes had contributed to its poor crash history."
So for 30 years, KAL was crashing planes at the rate of about one every other year. The situation did improve after the review, but there was still an unintended off-runway landing in 2007, and of course the SFO crash (which is not mentioned in the article at all -- someone needs to go update it).
http://en.wikipedia.org/wiki/Korean_Air_incidents_and_accide...
"Korean Air had many fatal accidents between 1970 and 1999, during which time it wrote off 16 aircraft in serious incidents and accidents with the loss of 700 lives. The last fatal accident, Korean Air Cargo Flight 8509 in December 1999 led to a review of how Korean cultural attitudes had contributed to its poor crash history."
So for 30 years, KAL was crashing planes at the rate of about one every other year. The situation did improve after the review, but there was still an unintended off-runway landing in 2007, and of course the SFO crash (which is not mentioned in the article at all -- someone needs to go update it).
That blog writer is a Korean American lawyer and easily hated for his inaccurate and biased reporting of Korean topic. He arrogantly claims to represent his erroneous views as what majority of Koreans think.
Who do I trust more, some biased Korean American lawyer who hates his job and rants online, or an officer who trained Korean pilots, witnessed that the Korean culture produces incompetent pilots?
Who do I trust more, some biased Korean American lawyer who hates his job and rants online, or an officer who trained Korean pilots, witnessed that the Korean culture produces incompetent pilots?
I grew up in Korea and know very well of the culture in Korean society. It's basically a military hierarchy with people older than you, automatically being at a higher position in society. You do not question, it's considered "rude".
Having lived outside of Korea, I can completely understand the possibility that Korean culture plays a role in job areas where teamwork and hierarchial culture clash with common sense and the ability to express it freely without social barriers or repercussions.
I see a lot of fellow Koreans defending that culture is not responsible for producing incompetent pilots but based on what I've read, from that officer who have trained Korean pilots and have witnessed a near 90% failure rate on the flight simulation involving manual airplane control, I'd have to say I'm pretty fucking worried.
It's totally unfair to cry "STEREOTYPING!" or "THATS RACIST". I really don't give a flying shit, you are not changing the culture (or more like can't change it because it's considered an essential core identity of Korean culture) that produces shitty pilots, you are not flying my plane.
It would be fine if Asiana just accept it and try to change the root problem which is the hierarchial social barrier present in Korean culture clearly incompatible in this particular industry of flying airplanes where teamwork and ability to express one's opinion and observations without fear of repercussion or coming across as rude and losing face.
For now, if it's Asiana or KAL, I am not fucking getting on that plane.
It's one thing to be proud of our culture but it takes a bigger courage to accept that not all of it is compatible with new technological jobs, and finally fix it.
Having lived outside of Korea, I can completely understand the possibility that Korean culture plays a role in job areas where teamwork and hierarchial culture clash with common sense and the ability to express it freely without social barriers or repercussions.
I see a lot of fellow Koreans defending that culture is not responsible for producing incompetent pilots but based on what I've read, from that officer who have trained Korean pilots and have witnessed a near 90% failure rate on the flight simulation involving manual airplane control, I'd have to say I'm pretty fucking worried.
It's totally unfair to cry "STEREOTYPING!" or "THATS RACIST". I really don't give a flying shit, you are not changing the culture (or more like can't change it because it's considered an essential core identity of Korean culture) that produces shitty pilots, you are not flying my plane.
It would be fine if Asiana just accept it and try to change the root problem which is the hierarchial social barrier present in Korean culture clearly incompatible in this particular industry of flying airplanes where teamwork and ability to express one's opinion and observations without fear of repercussion or coming across as rude and losing face.
For now, if it's Asiana or KAL, I am not fucking getting on that plane.
It's one thing to be proud of our culture but it takes a bigger courage to accept that not all of it is compatible with new technological jobs, and finally fix it.
These were fairly veteran pilots. One was new on type, but he had a check captain sitting next to him.
The one who was in the left seat was a graduate of basic flight school based in Florida somewhere.
Not sure where the right seat pilot learned basic flying but obviously he's experienced enough to be a training pilot.
The one in the back jump seat was a graduate of ROK AF Academy and flew F5 and F16 before joining Asiana Air. He was youngest (least # of hours) of the 3 pilots in the cockpit?
Not sure where the right seat pilot learned basic flying but obviously he's experienced enough to be a training pilot.
The one in the back jump seat was a graduate of ROK AF Academy and flew F5 and F16 before joining Asiana Air. He was youngest (least # of hours) of the 3 pilots in the cockpit?
The guy in the left seat was a very experienced pilot. From the article:
"The Pilot Flying was in the left seat. He was a captain transitioning from the Airbus 320 to the Boeing 777. He had 9,700 hours flight time with less than 45 hours in the Boeing 777."
That's almost as many hours as the instructor had (12,000 hours).
"The Pilot Flying was in the left seat. He was a captain transitioning from the Airbus 320 to the Boeing 777. He had 9,700 hours flight time with less than 45 hours in the Boeing 777."
That's almost as many hours as the instructor had (12,000 hours).
It brings up an interesting conundrum. The more that pilots use autopilot for approach, the less feel they have for what the controls should feel like at the correct airspeed. However, if we just outright ban auto-pilot for approach, there is more room for human error...
This is basically why they created the flight director. http://www.flyingmag.com/wonder-flight-director
With it you get the hands-on feeling of flying the plane with the precision of AP/ILS information.
With it you get the hands-on feeling of flying the plane with the precision of AP/ILS information.
I'm not a pilot, but the ability to set the throttle to idle (including all auto-controls) while the plane is in the air without warnings seems dangerous to me. It sounds like a better indication that there was no thrust may have helped the pilots recognize the error sooner.
Flying at idle throttle is completely normal when descending from cruise to final approach. What's not normal is certain patterns of airspeed and altitude loss, and I agree, you could probably come up with better indicators for that.
It's not unbelievable using idle thrust in the air. It's inexcusable to not watch your air speed though.
That's my thought. I can think of a few times where it might make sense, mostly to burn off speed or altitude; but if you're that low and already under the suggested approach speed it seems like it's almost certainly a mistake.
I'm surprised they had to get so low before the stall warning system kicked in (given the speed and throttle position).
I'm surprised they had to get so low before the stall warning system kicked in (given the speed and throttle position).
The solution is combination of more automation and more communication to the user (pilots).
According to the Wikipedia article on the crash, a feasibility study was added to FAA appropriations this year for a verbal warning for low speed. So this may be a practical way to improve communications if it pans out.
Excellent. With current sensor data (GPS, air speed, control surface positions, engine output), a physics engine, and map/synthetic radar data, it is possible to politely tell a crew that they're a) doing something wrong and b) how to correct it quickly.
Yeah, it seems like there should be a big red light on the air speed indicator that says it's under the pilot's control.
How much control do we take away though? I'm a private pilot, but also an automation fanatic. Software doesn't get tired, it doesn't have a bad night of sleep. If its well written, it has a much lower failure rate than humans.
The ILS wasn't working, but the GPS was. All major and most minor airports have approach plates/terminal procedures. Calculate the desired glide path to touchdown on the runway. Display on a MFD (multi function display) plane, glide path, runway. Proper glide path? Green backlight. Outside of margin glidepath? Yellow backlight. Fall within dangerous limits near the ground? Red backlight, engage autopilot (to go to hold position indicated by approach plates), go to full power, and disable pilot input until above safe altitude (props if you notify control via ADS-B of go-around due to human error).
http://en.wikipedia.org/wiki/Approach_plate
"Approach plates are essential for an airplane to make a safe landing during instrument meteorological conditions (IMC), such as low ceilings or reduced visibility due to fog, rain, or blowing snow. They provide specific waypoints and altitudes necessary to line an aircraft up with a designated runway for landing, as well as important navigational information, such as radio frequencies of navigational aids and required course headings, and the prescribed minimum visibility requirements to execute the approach."
http://flightaware.com/resources/airport/KSFO/procedures
Runway 28L approach plate:
http://flightaware.com/resources/airport/KSFO/IAP/ILS+RWY+28...
The ILS wasn't working, but the GPS was. All major and most minor airports have approach plates/terminal procedures. Calculate the desired glide path to touchdown on the runway. Display on a MFD (multi function display) plane, glide path, runway. Proper glide path? Green backlight. Outside of margin glidepath? Yellow backlight. Fall within dangerous limits near the ground? Red backlight, engage autopilot (to go to hold position indicated by approach plates), go to full power, and disable pilot input until above safe altitude (props if you notify control via ADS-B of go-around due to human error).
http://en.wikipedia.org/wiki/Approach_plate
"Approach plates are essential for an airplane to make a safe landing during instrument meteorological conditions (IMC), such as low ceilings or reduced visibility due to fog, rain, or blowing snow. They provide specific waypoints and altitudes necessary to line an aircraft up with a designated runway for landing, as well as important navigational information, such as radio frequencies of navigational aids and required course headings, and the prescribed minimum visibility requirements to execute the approach."
http://flightaware.com/resources/airport/KSFO/procedures
Runway 28L approach plate:
http://flightaware.com/resources/airport/KSFO/IAP/ILS+RWY+28...
How much? I don't think the pilot should have the authority to fly the plane into the ground, at least not without cutting out several circuit breakers.
In this case, it clearly appears that a computer could easily have looked at the altitude, attitude, air speed, and thrust and decided with enough time to recover that the meat module was malfunctioning, and could have initiated a go around.
Also, it's pretty clear that the automation could have started yelling LOLWUT or whatever the industry jargon is for exceptionally inconsistent inputs, such as flight level change mode on final.
In this case, it clearly appears that a computer could easily have looked at the altitude, attitude, air speed, and thrust and decided with enough time to recover that the meat module was malfunctioning, and could have initiated a go around.
Also, it's pretty clear that the automation could have started yelling LOLWUT or whatever the industry jargon is for exceptionally inconsistent inputs, such as flight level change mode on final.
The aircraft was landing. It was supposed to (gently) fly into the ground. A lot of automatics are disabled below a certain altitude and/or when landing gear are extended because otherwise they would prevent landing. A landing is essentially stalling the aircraft just before the wheels touch.
Almost all recent commercial aircraft have autoland [http://en.wikipedia.org/wiki/Autoland] which will bring the aircraft down from cruise phase to the taxiway in a fully automated fashion.
"Autoland systems were designed to make landing possible in visibility too poor to permit any form of visual landing, although they can be used at any level of visibility. They are usually used when visibility is less than 600 meters RVR and/or in adverse weather conditions, although limitations do apply for most aircraft—for example, for a Boeing 747-400 the limitations are a maximum headwind of 25 kts, a maximum tailwind of 10 kts, a maximum crosswind component of 25 kts, and a maximum crosswind with one engine inoperative of five knots. They may also include automatic braking to a full stop once the aircraft is on the ground, in conjunction with the autobrake system, and sometimes auto deployment of spoilers and thrust reversers."
"Autoland requires the use of a radar altimeter to determine the aircraft's height above the ground very precisely so as to initiate the landing flare at the correct height (usually about 50 feet (15 m)). The localizer signal of the ILS may be used for lateral control even after touchdown until the pilot disengages the autopilot. For safety reasons, once autoland is engaged and the ILS signals have been acquired by the autoland system, it will proceed to landing without further intervention, and can be disengaged only by completely disconnecting the autopilot (this prevents accidental disengagement of the autoland system at a critical moment). At least two and often three independent autopilot systems work in concert to carry out autoland, thus providing redundant protection against failures. Most autoland systems can operate with a single autopilot in an emergency, but they are only certified when multiple autopilots are available."
"Autoland is highly accurate. In his 1959 paper [2] John Charnley, then Superintendent of the UK Royal Aircraft Establishment's Blind Landing Experimental Unit (BLEU), concluded a discussion of statistical results by saying that "It is fair to claim, therefore, that not only will the automatic system land the aircraft when the weather prevents the human pilot, it also performs the operation much more precisely"."
"Autoland systems were designed to make landing possible in visibility too poor to permit any form of visual landing, although they can be used at any level of visibility. They are usually used when visibility is less than 600 meters RVR and/or in adverse weather conditions, although limitations do apply for most aircraft—for example, for a Boeing 747-400 the limitations are a maximum headwind of 25 kts, a maximum tailwind of 10 kts, a maximum crosswind component of 25 kts, and a maximum crosswind with one engine inoperative of five knots. They may also include automatic braking to a full stop once the aircraft is on the ground, in conjunction with the autobrake system, and sometimes auto deployment of spoilers and thrust reversers."
"Autoland requires the use of a radar altimeter to determine the aircraft's height above the ground very precisely so as to initiate the landing flare at the correct height (usually about 50 feet (15 m)). The localizer signal of the ILS may be used for lateral control even after touchdown until the pilot disengages the autopilot. For safety reasons, once autoland is engaged and the ILS signals have been acquired by the autoland system, it will proceed to landing without further intervention, and can be disengaged only by completely disconnecting the autopilot (this prevents accidental disengagement of the autoland system at a critical moment). At least two and often three independent autopilot systems work in concert to carry out autoland, thus providing redundant protection against failures. Most autoland systems can operate with a single autopilot in an emergency, but they are only certified when multiple autopilots are available."
"Autoland is highly accurate. In his 1959 paper [2] John Charnley, then Superintendent of the UK Royal Aircraft Establishment's Blind Landing Experimental Unit (BLEU), concluded a discussion of statistical results by saying that "It is fair to claim, therefore, that not only will the automatic system land the aircraft when the weather prevents the human pilot, it also performs the operation much more precisely"."
Autoland isn't a matter of simply pressing 'land'. The airport and aircraft have to be specially equipped, and the pilots properly certified. Very new, and older very large aircraft (Boeing/Airbus) are equipped with Autoland.
The aircraft has to support it, but the airport/runways no longer need to. ILS is being deprecated for synthetic glidescopes using GPS, as your precision is higher. DGPS is installed at the airport for increased position resolution, but the aircraft can fail back to WAAS in the event DGPS is unavailable.
They do. Autoland requires a CAT II/III ILS. WAAS is very accurate and will surely be used for this purpose in the future, but it isn't at the moment.
I'm sure I don't have to point out the obvious difference which is that a landing ends with a vertical speed that asymptotically approaches zero whereas a crash also has a terminal vertical speed of zero (obviously) but with a discontinuous derivate and a rather high vertical speed at t minus episilon.
The computer should be able to differentiate between situations where some plausible sequence of pilot actions will result in success, and one where no such success is possible.
The computer should be able to differentiate between situations where some plausible sequence of pilot actions will result in success, and one where no such success is possible.
What happens when the automation malfunctions and wants to fly the plane into the ground?
Plenty of aviation accidents boil down to conflicts between different automated systems, or between automated systems and pilot's senses, and there is no universal criterion for deciding which one should win.
Plenty of aviation accidents boil down to conflicts between different automated systems, or between automated systems and pilot's senses, and there is no universal criterion for deciding which one should win.
It's common sense: the human pilot is always responsible and therefore MUST ALWAYS have the final say. Period. There can be plenty of warnings, but automating too much machine behavior (Airbus methodology) has unintended consequences:
- 0. Less control over the machine's behavior atrophies pilot's situational awareness. Boeing requires a deeper understanding of how the machine behaves and hence what's permissible.
- 1. Reduces an experienced pilot's potential recovery options.
In this case, three clowns stalled a perfectly working multimillion-dollar craft into the ground and killed a few people (it could have been significantly worse). I wouldn't let these jokers fly Flight Simulator, they're liabilities.
- 0. Less control over the machine's behavior atrophies pilot's situational awareness. Boeing requires a deeper understanding of how the machine behaves and hence what's permissible.
- 1. Reduces an experienced pilot's potential recovery options.
In this case, three clowns stalled a perfectly working multimillion-dollar craft into the ground and killed a few people (it could have been significantly worse). I wouldn't let these jokers fly Flight Simulator, they're liabilities.
"How much control do we take away though?"
I think it's less about "how much do we take away", and more about "if we automate this, will we train dangerous habits into pilots who use it?"
You don't tech you junior sysadmins to use "rm -rf /" to delete user data "because Unix prevents you from deleting files not owned by you, so it's perfectly safe!" _one day_ that sysadmin is going to be logged in as root.
I have no idea whether the pilot here was trained to let an Airbus override dangerous actions on his part or not - but if he _was_ – _that's_ something that ought to be considered for changing.
We wouldn't let a car manufacturer sell a car with the brake pedal on the right and the accelerator on the left - because no matter how diligently you tell buyers, or how prominently you point it out in the owners manual, somebody is going to mash that accelerator pedal in an emergency expecting the car to stop.
I think it's less about "how much do we take away", and more about "if we automate this, will we train dangerous habits into pilots who use it?"
You don't tech you junior sysadmins to use "rm -rf /" to delete user data "because Unix prevents you from deleting files not owned by you, so it's perfectly safe!" _one day_ that sysadmin is going to be logged in as root.
I have no idea whether the pilot here was trained to let an Airbus override dangerous actions on his part or not - but if he _was_ – _that's_ something that ought to be considered for changing.
We wouldn't let a car manufacturer sell a car with the brake pedal on the right and the accelerator on the left - because no matter how diligently you tell buyers, or how prominently you point it out in the owners manual, somebody is going to mash that accelerator pedal in an emergency expecting the car to stop.
I agree! Personally, I would rather fly on a plane with no pilot that's driven completely with UAV guts from takeoff to landing. Yes, there will be edge cases where there will be failures. I just believe those cases will be far fewer than pilot error. AND with the resulting data, we can prevent those same edge cases from occurring again.
UAVs are still piloted. They're just controlled from the ground.
Not all UAVs:
http://en.wikipedia.org/wiki/Northrop_Grumman_X-47B
The X-47B receives commands from the flight deck, but is not directly piloted. It not only can be catapulted from an aircraft carrier, fly its mission, and return with no human input, it can also autonomously on-air refuel from a tanker with no human pilot on the ground.
http://en.wikipedia.org/wiki/Northrop_Grumman_X-47B
The X-47B receives commands from the flight deck, but is not directly piloted. It not only can be catapulted from an aircraft carrier, fly its mission, and return with no human input, it can also autonomously on-air refuel from a tanker with no human pilot on the ground.
Maybe piloted is the wrong word. It's not AI. They're still directed and monitored by an operator.
<cynical thought>Remotely piloted by guys who aren't sitting at the pointy end of 100 tons of jetfuel doing 600mph, and therefore might not be quite as well motivated to succeed as their in-jetliner colleagues…
Not for you tho', as getting the data killed you!
Still an improvement over people. You know what goes wrong, but you have no guarantee other pilots own't make the mistake again, even with training and education.
I guess the biggest question I'm left with after this is how professional pilots can make this kind of elementary piloting mistake: Not watching the airspeed on final approach, and not reacting immediately when the PAPI indicates that the aircraft is too low. I was left with the same kind of question after the Air France disaster; this plane was stalled straight into the ocean from cruising altitude. It's a big mystery to me how three pilots could overlook this condition for four minutes. Maybe this is just the kind of fluke accident that will happen sometimes when you have ten thousand airliners in the sky every day. But it seems like a good idea to investigate whether pilots rely too much on the computers and forget the basics.
Regardless, let's not draw any conclusions until the investigation has had its say. It's okay to speculate, but I feel that it doesn't provide a lot of benefit to go into detailed scenarios when the complete picture is unknown.