Bug identified after Alaska Airlines planes bump runway while taking off

The airline completely grounded their entire fleet while they investigated this issue, so I don't really understand why you're trying to act like nobody took this seriously. The article makes it quite clear this was handled as a serious problem and steps taken.

The Alaska Airlines' pilots union is both qualified to have an opinion AND looking out primarily for their members (i.e., pilots), and they had this to say:

> The data “confirms that the airplane was safely airborne with runway remaining and at an altitude by the end of the runway that was well within regulatory safety margins,” said the union’s Alaska unit chair, Will McQuillen, in a statement.

If the union was unhappy with the remediation steps taken, they'd say so. That is quite literally their primary function.

- Pulled over onto the shoulder,

- Passed around a pad to collect everyone's contact information,

- Summoned a replacement bus, and

- Called the provincial police to escort us along the shoulder to the replacement bus.

In the moment, all of this felt a little over the top, and the total delay of about 20mins total was pretty frustrating given that I ended up missing a connection. But at the end of the day, it builds my trust in the safety of that system that the fitness of any particular piece of equipment is not up to the individual drivers to judge— part of paying for a ticket on the state-run transit system is expecting a higher level of safety than, say, what you might get on a Chinatown bus line (https://en.wikipedia.org/wiki/Chinatown_bus_lines#Accidents). And I think I was also glad that it hadn't happened to me in my personal vehicle, where I would have to be the one to assess fitness and then deal with the insurance and so-on in the aftermath.

If I felt a bumper or tire bump when I was parking I would not care.

I was pointing out that the article described a course of action that, in fact, sounds serious to a layperson. It seems to me that "land and have a required inspection" is an indication of seriousness, not an indication of downplaying the severity.

You said, "The article downplayed the seriousness of a tail strike." I was pointing out that the thing they described multiple times did not sound like downplaying to me, as a layperson. "They immediately landed," sounds serious. "They grounded the fleet," sounds serious. "The planes required inspection before being allowed to fly," sounds serious. Nothing in the article reads to me, as a layperson, as if they were saying a tail strike is not serious.

I am saying that the article said things that sound severe, as a direct response to the claim that the article downplayed the seriousness.

Aircraft age isn't in years, but in number of pressurisations (takeoff/landing cycles). A low cost airline optimising their schedule to squeeze every second of their airframe with constant short distance hopping around would result in much more of those compared to a legacy airline's widebody that is flown daily on a very long flight. So it depends on aircraft type/size and usage patterns, but Ryanair's 737 will be able to handle less years than DHL's 767Fs.

So for the 747 in the story, 22 years is on the long end, but not unheard of.

For small non-pressurized aircraft that people do their initial training in, it's very normal to learn in a plane that is more than 60 years old.

If you are going to factor the rest of the world into it, why do you need to isolate the calculatons to the plane?

I have the idea that a captain is responsible for its flight, and thus want to have as much information as possible. I think flights have their own full manifest anyway, so they have all the information you mentioned?

As to "how", I'm not sure I understand the issue, can't the same computations be done locally? The computations you mention doesn't sound too computing intensive.

I concur with sibling "Why does this seem so absurd to you?". You probably know real reasons for this not to be done from aircraft, and we're curious to see some.

Pilots carried a paper performance manual for the aircraft and did the necessary calculations during preflight, I believe - though they stopped doing this because the computerised figures were much more accurate and reliable.

To reduce the risk of this sort of thing happening. I imagine aircraft software standards are a bit better than whatever standards this software uses, if it failed simply due to high load.

> and how?

I'm pretty sure the computer on an aeroplane can handle this simple computation.

Edit: And even still, international regulations will vary and so the aircraft carrying two different sets of regulations seems complicated I would think?

> That morning, a software bug in an update to the DynamicSource tool caused ...

This says when the bug happened, not when the update was made.

Would have thought lower than ideal safety margins on takeoff speed (the calculations were apparently <20% off the true value) were a more concerning problem

There is still the matter of dealing with mutable stores like databases, but well-written code would make that impossible as well, plus permit tests to run concurrently

It's often a judgement call when things don't happen quite right and I don't think our technology is anywhere near ready to hand the abort process over to the plane's programming.

The fact that it was not communicated in the training and manuals was a result of lobbying by the airlines.

I would suspect that certification would break down at some point; does a plain old calculator need to be certified? Certainly not, but I'd imagine the FAA or whoever if asked would prefer pilots use calculators than do everything by hand.

I'm curious about EFBs as well - I run W&B for my little bugsmasher in Foreflight. Has that gone through certification? Certainly someone from the FAA wouldn't have to review every release for that if so...

So when does certification come into play versus it just being another tool that pilots are responsible for validating?

For example in that incident in Ireland where crew erroneously told their jet plane it was very, very cold, and then (cold air is dense, less power needed) they barely had enough thrust to take off before they ran entirely out of runway - that was partly caused (Swiss cheese model) by the pilots being issued with software that didn't make it easy for them to cross check the facts they can eyeball. Is it certain they'd have realised if their software did show this information - like the software issued to similar crews with other outfits? No, but that's one more opportunity for everybody to not die, and the whole point of the Swiss cheese model is that lots of things have to go wrong or else you're fine.

One of the other potential mitigations for that incident illustrates where human eyeballs don't help. In principle a human pilot could realise they aren't accelerating enough. In practice humans are lousy at estimating acceleration to the tolerance needed so this isn't effective unless you use the same strip so often that your brain learns exactly how things ought to look.

However thanks to GPS a machine can measure acceleration very well, and it can know how long your chosen runway is and what its take off speed is - so it can estimate if you're accelerating enough and the latest models can announce "Caution: Acceleration" early in the take off roll, before V1, which means the crew can abort and check why they didn't have the intended acceleration - regardless of the cause.