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Comment by mulmen | Hacker News Reader

Europe uses pessimistic runway locks but the US prefers optimistic locks. This improves throughput at US airports with the risk of a rollback on a dirty runway.

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It happened before dawn this past Saturday, in near zero-visibility conditions, [...] on a “Cat III” approach that allows an airliner to touch down safely even if the pilots cannot see the runway.

Seems like this would be a good trigger to switch temporarily to a more pessimistic strategy. (Caveat: I don't know anything about aviation.)

I'd be curious to know how much it actually improves throughput. It seems strange to use optimistic locks in such a safety critical process, when a more fail-safe approach is available.

Sounds like a money problem to me. Less time between planes means more planes means more money.

It sounds to me like far too many critical safety decisions are being made with an eye on money rather than safety. There were reports warning that Fukushima wasn't safe in case of a tsunami, but the company in charge of the plant decided to ignore that. Deep Water was caused by cost cuts. The Boeing 737 Max was made for financial reasons, fixing a fundamental hardware problem in software.

Safety engineers clearly need a bigger say in these things.

> Sounds like a money problem to me. Less time between planes means more planes means more money.

Everything is a money/greed problem if you look at it through the lens of motivated reasoning.

The usage of infrastructure is mutually beneficial. The airport, the various businesses operating at it, the customers, everyone benefits per flight. Likewise you want to make that infrastructure get used as much as possible.

Would you be complaining about greed if a subway was running trains close together?

But why does it work fine everywhere else ? It's not like we all follow the US model, yet our airports are fine and our airplanes dont crash over silly cost cuts.

There must be something the americans do wrong, somewhere, and optimisation cannot be an excuse for mediocrity. Do it fast and safe or do it slow and safe: the passengers can wait, or build their own planes and airports if they think they can do better.

Are American airports statistically less safe than other ones? Seems like you are assuming this is the case in your comment, but have you actually checked?

Risk will always exist. Our most precious resource is time. Every effort to save it is worth it. What if it causes one accident every 20 years? It saved thousands of years of human time in the meantime.

Based on Google numbers:

There’s 16M flights per year, so saving 5 minutes each is 80M minutes, which corresponds to 160 years.

A plane crash will kill about 160 people; so if one happens every twenty years, then we’ll have saved lives if the average age is over 50 (within 20 years of natural death) and lost lives otherwise.

Personally, seems a bad gamble.

To get from minutes of time to minutes of human time, you have to multiply the 5 minutes by the number of passengers on the flight

I don't have an opinion one way or the other on the "optimization", just pointing out the missing step in the math

I'm not sure a one to one comparison here is appropriate, either. The fundamental argument that 1 minute of wasted time is equivalent to 1 minute of life seems tricky. To prove this is easy, simply ask yourself if you'd rather take a day off your life or spend a day waiting in line at the DMV. I think you'll find that most people would rather still be alive and at the DMV. Loss of life is not equivalent to loss of time.

It is the same thing. Life is finite. You will live every minute, but you better not waste most of them. Last thing you want is to run out of time and not done the things you wanted.

Say I offer to stand in line for you at the DMV and do all your paperwork that otherwise would have taken a day of your life, but in exchange at some point in the future, 1 day from your otherwise natural death, I will find you and shoot you in the head. say I have the resources to absolutely do this and there's no way to avoid it.

Do you take that deal? Why or why not?

Yes. Chances are high my natural death will occur at old age. One day today is worth more than one day as an old man.

What you’re suggesting is any crash can be attributed to the US method of scheduling takeoff and landing (since that’s the risk issue you’re responding to). That’s not true. If a plane’s engine explodes in midair, it has nothing to do with how the ATC schedules takeoff and landing.

I couldn’t find any crashes listed on Wikipedia in the past 20 years that could be attributed to two planes being directed occupy a runway at the same time.

I remember when my grandfather and I were arguing about whether or not SNES or Sega Genesis was better(he worked for Motorola who made the Sega Genesis processor). Eventually we agreed that whichever one had more buttons on its controller was the superior product, so I won that discussion. Actually I think he was just ready to end the argument but I thought my logic was sound.

If time is our most precious resource, then build more runways. The problem is that they cost more money to build and more money to operate. So we go back to

>> It sounds to me like far too many critical safety decisions are being made with an eye on money rather than safety.

Money is not the only problem at most locations

Major Airports are often locked in to the Physical foot print either due to Geography or other factors. Sure you can just "move the airpoirt" but then you have the NIMBY problem where everyone wants an airport close by, but never near by....

And if you want to simplistically run it all down to "money" well at that point everything is a money problem, so for like NYC; they could spend billions or Trillions to turn midtown into a big airport, but that seem rather unrealistic.

This narrative that came out of COVID of "if it saves just one life" is a bit ridiculous imo, and not at all practical

At some point, you can build a new airport that is basically hell and gone from the city it serves--such as DIA outside Denver, which had all sorts of problems getting going. But you can't really materially expand close-in airports. And in case anyone thinks this is a uniquely American problem, how long did it take Germany to build a new Berlin airport again?

Your eye must necessarily be on both money and safety. If you look at only one, you will only make nonsensical decisions.

I don't know the analysis for the multiple clearance on runways on the US (honestly, it's the first time I hear about it). What I know is that the US has many complex risk analysis that my country (3rd largest aviation area on the world, after the US and EU) doesn't have enough data to replicate. That leads to plenty of policies that we can't actually understand the reasoning.

It takes people's time to build runways. That's time they won't be building other valuable things.

You're ignoring the core truth of the comment you're replying to: Scarcity exists. There is no way to have it all; there are only compromises. Simply walking is dangerous because you could fall. We could all go back to being infants* crawling on the floor if we wanted to be safer. But we won't. Making more compromises in the name of safety has to be justified. Planes will never be perfectly safe. That is okay.

You’ll likely still have to spend that time after the horrific accident.

Also, I would disagree that engineering time is more valuable than human life. Engineering time should be spent on safeguarding human life. Otherwise, what are we even doing?

New York is upgrading its subway signalling system [1] from pessimistic to optimistic. Sure, denying entry into an occupied block to the next train prevents collisions. But it also wastes time, energy and money. If there is an emergency on the held train, it’s longer to the station. To say nothing of the added wear and tear starting and stopping entails.

[1] https://en.m.wikipedia.org/wiki/Signaling_of_the_New_York_Ci...

People tend to complain about the safety of airplane even though it is in the top echelon of safe modes of transit. There's no reason to try to reach the highest-hanging fruit trying to make it even safer when people are dying in droves on the road just getting to the airport. Much better to do something about that low-hanging fruit.

This doesn't make much sense, IMO. Road safety and air travel safety are orthogonal tasks. We can and should do both things.

Putting out a housefire and going to the dentist are also orthogonal tasks. GP’s point is very clearly that we should budget limited political will.

The patient has an abscessed cavity, they must evacuate the house and go to a dentist. Both after all.

If that's your reasoning, then you don't understand what money is. It's a proxy for other things. Saying you're doing something with "an eye on money rather than safety" is meaningless. Substitute whatever else the money could have bought. E.g., doing something with "an eye on apartment building safety rather than aviation safety". Then you can have a discussion.

Do airlines invest their profits into apartment safety?

Of course not, silly. The airline's owners do.

Really? Apartment safety rather than stock options or yachts? I've got to say I'm a bit skeptical.

Maybe you're getting lost in the details, then. This is what markets do. They facilitate complex tradeoffs between scarce resources. More aviation safety means less of something else.

You imagine that the something else is something you don't care about or think doesn't matter - like executive compensation. Well, you're like everyone else - we all think we should be running the country.

The last commercial plane wreck in the US was in 2009 and was a small commuter crash with only 49 fatalities[1]. This does not even make the Wikipedia list[2] of deadliest crashes which shows none since 2001. Bureaucratic over reaction to rare events can create worse problems overall for society than not changing anything at all. Just see the US response to 9-11. The American people solved the problem in about 90 minutes. Don't let plane hijackers control the plane. Fight back instead of just wait. Thus UA flight 93. The lesson from that should have been a very measured "We need solid, locking, cabin doors on airplanes". That's it. Not the whole TSA department stand up, 20 year war in Afghanistan, invade Iraq????, Patriot Act forever with secret courts bullshit craziness. Instead of "never let a crisis go to waste" we need the State to be more slow to judgement.

[1]https://www.cnbc.com/2019/02/13/colgan-air-crash-10-years-ag... [2]https://en.wikipedia.org/wiki/List_of_accidents_and_incident...

It's worth noting that the ICAO system is not perfect from a safety point of view: it often results in the controller saying 'Expect late landing clearance' instead, and clearance to land very close to the ground. As an ICAO-based pilot, I genuinely don't know which is safer. (And I also don't think the difference was important here.)

I tend to disagree that it was not important here.

At least it would have forced the controller to verify that SW is clear of the runway before clearing fedex.

As it was, it cleared both and then did something else until the situation was over.

Well I mean there are many optimistic stuff in american culture that seem nonsensical to us Europeans: for instance giving everyone guns to protect against the government's army is an optimistic view of human nature and I d rather give no gun to anyone instead :D

You wouldn't even have the opportunity to make these peanut gallery potshots if those overly optimistic Yankees took the British/French/German route and did not give the general public access to ATC recordings.

I can agree that the american transparency is a model, even if it fails some rare times (what I hate the most is when they do the whole circus around a terrible lie, with all the appearance of transparent government, but it's rare enough to be forgiven).

Not sure what is has to do with the initial problem that spawned the transparent mea culpa though, which is due to a sort of reckless optimism and an inability to look abroad for better ideas. I think they call it "American Exceptionalism" or some such there ? Even your answer seems to be that you fucked up but at least you're not as bad as ... the French ? What ? :D

I didn't say "at least we're not as bad as the French". I said you don't know how bad the French (or whoever) are because they don't share the same level of details.

If you bothered to comprehend what I wrote I'm pretty much advocating the opposite of American exceptionalism. The accident rate is pretty close across the first world. Why would the close call rate be substantially different?

Thank god aviation policy isn't dictated by people like you who have an ideological bone to pick.

I'm not sure why this is a problem with airports with two runways (doesn't Austin have two?).

I've been in a helicopter hovering over Heathrow airport where you can see the lights from the line of planes coming in to land every 45 seconds that looks like it goes off to infinity. Whatever technique they use there seems to work.

I assume it leads to a longer "cleared approach" phase and a shorter "cleared to land" phase and as a courtesy to the pilot behind, clearing the runway as quick as possible.

Taking a quick look at Heathrow approach, looks like runway is clear of the first plane landing when the following plane is 1-2 miles out and around 500ft.

For the most part, Heathrow doesn't do mixed-mode operation (where you have takeoffs and landings on the same runway). However, my understanding is that this is not for safety reasons, but mostly to give people living under the flight paths some periods of respite from the noise. They did use mixed-mode single-runway operation for a while during covid.

https://www.heathrow.com/company/local-community/noise/opera...

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