phdp · HackerTrans

vor 7 Monatendiscuss

Epicycles in a geocentric model of the solar system is another way of looking at planetary motion. It breaks down due to the required addition of complexity to explain discrepancies between the model and truth, which is the same for this particular situation. In addition to what the CPA said, how does this model work with callable, putable, or floating rate bonds where the interest payment is not known up front?

phdp

letztes Jahrdiscuss

No it isn’t! The headline they used is “Protecting Our Customers - Standing Up to Extortionists.” My issue with it is that they word their announcement in a way that leads people to congratulate them instead of saying we’re sorry for leaking your private information. I’m so angry at them over this.

Additionally the email they sent me had the subject “important notice” and that my personal account was affected as the third sentence in a rather wordy paragraph. None of this is ok and this is not a company taking this seriously.

phdp

letztes Jahrdiscuss

My iphone can't kill someone else moving 70 mph down the highway during the normal course of its operation.

phdp

vor 3 Jahrendiscuss

Blackstone was never a division of Blackrock

phdp

vor 3 Jahrendiscuss

Blackrock is not buying individual houses. Are you confusing them with Blackstone, who did own a unit that bought and rented single family homes?

phdp

vor 4 Jahrendiscuss

Think of it as the opportunity cost. If interest rates are high, I can go out and buy a us gov't bond at x% risk free. This makes other investments that maybe looked attractive at lower interest rates less attractive now, and this is reflected in the lower npv value.

phdp

vor 6 Jahrendiscuss

No one else does what the USPS does. No one else does daily rural mail delivery. The USPS is also not tax subsidized.

phdp

vor 6 Jahrendiscuss

A solar sail doesn't work via aerodynamic lift. It works on conservation of momentum. Also, the biggest contributor to force on a solar sail is not solar wind, but radiation.

phdp

vor 7 Jahrendiscuss

I imagine that, just like airlines use futures to hedge the price risk of jet fuel, they do the same for their vast logistics operation. They can lock in prices so they aren’t suddenly facing a massive bill if gas goes way up.

phdp

vor 7 Jahrendiscuss

It is different though. The FDIC would force the bank into receivership and return the insured money to account holders. That doesn’t exist for tether.

phdp

vor 7 Jahrendiscuss

Philip Greenspun is not a no one when it comes to aviation.

https://philip.greenspun.com/flying/resume

While he doesn't have 737 experience, he's far from an armchair quarterback.

phdp

vor 8 Jahrendiscuss

He sent shorts to David Einhorn

https://markets.businessinsider.com/news/stocks/elon-musk-ma...

phdp

vor 8 Jahrendiscuss

I know quite a few finance companies use it - Morgan Stanley and Goldman Sachs come to mind.

phdp

vor 8 Jahrendiscuss

It’s largely there to sound scary. While stocks can have their exposure measured based on their face value, derivatives cannot. For example, you could have a 100 million interest rate swap, where you either pay or receive the difference between a floating interest rate and a fixed interest rate depending on their values. You’ll never get close to ever losing or gaining 100 million dollars, and that 100 million is never exchanged, but you still have that much exposure.

To further complicate things, these banks may have hedged their exposure, meaning they may have an equal but opposite interest rate swap. Now they have 200 million of exposure, but no matter how the interest rates have changed, there’s no risk (all of this assumes no counterparty risk, which may or may not be valid, but for now ignore it).

phdp

vor 9 Jahrendiscuss

Newt Gingrich too on Parks and Rec.

phdp

vor 9 Jahrendiscuss

Neither of those are fighting words.

See trope 7 from Ken White, a noted lawyer and first amendment expert - https://www.popehat.com/2015/05/19/how-to-spot-and-critique-...

phdp

vor 9 Jahrendiscuss

You don't. You pull up your password on your phone and type it in manually onto the computer.

phdp

vor 9 Jahrendiscuss

> Uhm, "traffic at terminal ends" suggests the real problem is that the correct path is not known in the beginning, or that autopilot might not be able to avoid collision on its own... which is quite a bit different from the plane being unable to locate itself accurately and follow the correct path even if it were known a priori. Are we even discussing the original issue at this point?

Your thesis of your statements is that it is ridiculous that there is no moving map for pilots to see on the airplane. You've been told directly by some commenters that there is (tuxer), and others, including me, have said that GPS is not the way to land a plane.

>I have no idea what that means. I'm not sure what gave you the impression that I know what that means either.

I mean this in a positive way, but you should look it up on wikipedia. There are many great articles about the systems in place for instrument approaches and landings, and you may learn something interesting for a quick 15 minute investment.

> My problem is whether GPS is accurate/reliable enough to lead the plane to the place where the next system can take over, which to me implies GPS is already certified to be accurate and reliable enough to get the plane near the correct runway. Read it again.

You call us out for dismissing your idea (And, as a computer scientist, what seems ridiculous to me is the idea that "Oh, but this system you just described won't work..."), which to mean seems to be some sort of GPS en-route to to landing automated system. This idea has been informed by your inaccurate reading of a CNBC article (So it seems clear in normal situations autopilot has plenty of positioning available to it, enough to find the runway and locate the plane on a display of some sort. That goes pretty clearly against what you said. Am I missing something?). The en-route exists but can often change from the time the plane leaves the ground to when it gets within 50-100 miles of the airport, at which time it might be disengaged and switched to VOR based navigation. The landing by GPS does not exist because it is a lot less accurate than the existing systems.

This branch of the thread is about auto landing, and you were talking about how it's absurd GPS is approved for automated flying. Given that GPS is used for en-route navigation and not landing, the assumption was that you were proposing GPS landing systems. That is what my comment is about. And yes, having autopilot disengage at 50 feet above the ground when the pilot is not expecting it can be fatal. I would say that for the landing stage it has to be all or nothing. And you've been suggesting cutting out the human component by proposing an system that goes from take off to landing without manual intervention! Even if there is still a pilot in the cockpit, it still takes a few seconds for the brain to spin up to take over a task from the computer.

It's awesome that as someone outside the aviation industry, you're curious about how it works. Your incredulous tone and sense of superiority (As a computer scientist, as if we should automatically and uncritically defer to your opinion, and I say that as a programmer) is a bit off-putting. If you had just done the basic amount of research you could have come back with a list of questions such as:

- Is GPS used to navigate planes from take off to landing? What else is used?

- Why was the pilot in this incident not using automation to land the plane? How often does this happen?

- What is the procedure for switching between different navigation technologies at different points of the flight? I know that take offs and landings can be manual, but when does autopilot kick in?

- Why is GPS not used to land planes?

- What equipment to pilots use in the cockpit? If they are not the latest and greatest, why?

We could then have had a proper discussion surrounding the need for backwards compatibility, the rolling out of ADS technology, how its absurd we still use voice over radio as a primary way of relaying commands, etc. Pilots and others in the aviation industry generally do believe that a lot of the technology guiding our largest planes is antiquated, but you trivialize it without understanding the full context.

phdp

vor 9 Jahrendiscuss

> OK, so I don't have much of an expectation for older plane models, but my interpretation of the above is that in newer models, autopilot need not disengage before landing and require manual intervention in order to align the plane with the correct track (barring bad weather or other unusual situations like bird collisions, etc.).

What is your definition of manual intervention? Pilots get updated instructions from the tower - the GPS path of the flight within 10 m is not programmed from the beginning due to weather issues, turbulence, traffic at the terminal ends, etc. The pilots hands may not be on the yoke, but they certainly are sending changes to the flight computer throughout the flight.

> So it seems clear in normal situations autopilot has plenty of positioning available to it, enough to find the runway and locate the plane on a display of some sort. That goes pretty clearly against what you said. Am I missing something?

Autopilot landings require a Cat III approach. There are currently no GPS (also known as GBAS for Ground Based Augmentation System) Cat III approaches approved in the US. The autopilot when landing is not using GPS for final approach. The pilot has pre-programmed in the waypoints labeled in the approach plate for the specific runway approach they've been told to take, and then they will switch over to the ILS approach.

The tone of many comments here (yours too) call out people who actually know how the system works and question them. The person you're trading comments with has said twice that GPS is not responsible for the autolanding portion of the flight. They even gave a summary of how instrument landing works - microwaves transmitted on specific frequencies in a specific pattern. You twice try to refute it. And then in your last paragraph you do exactly what he says the software engineers here do and you take offense to!

> sensible software engineers seem to regard aviation as a problem trivially susceptible of perfect solution

> And, as a computer scientist, what seems ridiculous to me is the idea that "Oh, but this system you just described won't work if there is a hurricane and there are turkeys getting rammed through our engines while the pilots are asleep and ATC happens to be on strike in the middle of a nuclear holocaust, so let's "be conservative" and never approve it because it's clearly going to make things worse on average".

Landing a big aircraft is not the easiest thing in the world, if only because the fate of hundreds of people rest in your hands. If you have a system that is designed to cut out the human component, it has to be all or nothing. As we learned from Asiana 214, when pilots have no actual practice doing something even in the absolute best of conditions and still cause loss of aircraft and life, how are they expected to perform when everything is going against them at the exact moment autolanding fails? Everything about flight training is preparing for the worst case, and practicing your skills over and over and over. Complacency can kill people when the margin of error between life and death is razor thin.

phdp

vor 9 Jahrendiscuss

It would be like looking at a map of California and expect to be able to get around San Francisco - the aeronautical charts are generally for long haul navigation purposes. There are approach plates for instrument landings, but for landing there you'd be looking at your instruments, which you've dialed into the correct runway, not the plate, in order to land the plane. In this situation, however, I can only imagine the pilot was on visual approach because otherwise the plane wouldn't have been lined up to land on the taxi way.