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Crisis over The Atlantic: The near crash of Air Transat flight 236

admiralcloudberg.medium.com

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Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#121

Post by MilStdJunkie »

silvestrov wrote: post #72
kqr wrote: post #47

The actual report: http://www.fss.aero/accident-reports/dvdfiles/PT/2001-08-24-... One of my pet peeves: the first 7 "causes and contributing factors" effectively blames the engine technicians for taking shortcuts. Nowhere does it say anything about the scheduling pressure from management that made the technicians consider shortcuts in the first place. If you have hiring and firing power and you tell someone they nee…

Also lack of access to documentation: the technician attempted to access the Rolls-Royce EIPC and the SB’s through the computer network, but was also denied access. This should be a major point for a maintenance shop. Documentation should always be available, both online and in offline versions.

So many problems involving tech pubs process here. I could almost classify this whole incident as a tech pubs problem, since the aircrew faults also involved the operational checklists and their planning/guidance.

TechPubs teams often have no control over the compliance (Optional, Mandatory, etc) of the SBs - that, at least in my experience, always came from way up high in the chain, sometimes from a VP who wasn't even tangentially involved in MRO. The required procedures - MX or ACRW - also are often coming from a costs concern, rather than criticality. The whole process of figuring out what's critical and what's not - that's a problem still being smacked into, every day.

It's not hard to make a Sanity Check for pubs vs ERP/PDM/CMMIS, but often people involved REALLY DON'T WANT TO SEE THAT. Because it's horrifying.

The commenter who mentioned HFACS is right on the money. Unless you implement something equivalent, you're gonna be chasing your own tail.

What a great article.

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#122

Post by bombcar »

ttcbj wrote: post #101
voxadam wrote: post #49

Earlier quoted context omitted.

I've been reading Admiral Cloudberg's write-ups for a few years since discovering them over on Reddit's r/CatastrophicFailure,[0] they're all truly excellent. I really enjoy his clear, no nonsense writing style. What us failure analysis nerds need, what we deserve, is a 90s era Discovery Channel show written by Cloudberg. Either that or a a United States Chemical Safety Board[1] style series. [0] https://www.reddit.c…

I just discovered cloudberg a few months ago, on HN. I agree the writeups are amazing. What I enjoy most is that frequently, the crash appears to have a clear “culprit” early on, then cloud berg points out 5-7 other factors, any one of which might have prevented the accident. If the series had a theme, I think it would be that airplane crashes are less about human failings than systemic ones.

That kind of thinking is useful when examining other system failures; AND it can be important to consider "let's assume this other factor had prevented the disaster, how could we have still identified the underlying 'cause'".

Because if your ass is being repeatedly saved by the equivalent of a $0.50 zip tie, you probably want to know that.

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#123

Post by ThinkingGuy »

robga wrote: post #33
cjrp wrote: post #25

Earlier quoted context omitted.

To cross the Atlantic with a twin-engined plane has that requirement (ETOPS).

This was a fun rabbit hole to go down, with the ETOPS [1] hint. I enjoyed the history of ETOPS-138 [0]. ETOPS-120 leaves some small triangles of the Atlantic inaccessible, particularly if one emergency airfield is unavailable. A 15% increase to 138 minutes covers it. Anecdotally, though, my experience as a commercial passenger feels like airlines fly almost directly over pacific islands rather than within X minutes o…

I recommend the Wendover Productions Youtube video on ETOPS:

https://www.youtube.com/watch?v=HSxSgbNQi-g

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#124

Post by oxryly1 »

madaxe_again wrote: post #52
noduerme wrote: post #34

Earlier quoted context omitted.

One of the coolest emergency airfields I can think of is, literally, Uruguay Route 9, along the coast of the country, where a 2-lane highway becomes an enormous runway that you continue driving along. I don't know if there were any famous landings there; I heard it's only used rarely by the Presidential jet. Here's where it is: https://goo.gl/maps/fpwxuPzGVDtDEKmB8 and what it looks like when you drive on it: https:/…

Hah! I was driving down this route a few years back when I suddenly found myself on an airstrip along with all the other traffic. It was particularly bizarre given that I’d just driven down from tacuarembo to punta del Diablo on largely unpaved roads. That said, it’s not the first road doubling up as a landing strip I’ve found myself on - there’s a stretch of the main road between Donetsk and Mariupol that was, in so…

That’s quite a variety of locales to find yourself driving in. What took you to all those places?

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#125

Post by jamincan »

bambax wrote: post #98
iso1631 wrote: post #93

Earlier quoted context omitted.

I'm amazed they can measure the distance between two real non-fixed components down to a few micrometers (they wrote 0.635mm, implying somewhere between 630um and 640um) If 0.635mm (an odd number itself which happens to be exactly 1/40th of an inch, or "25 thous" in American sizes) and they let it go that sounds really odd. That's literally the size of a grain of sand. If the concern is rubbing, sure that implies it…

0.635 mm is indeed an odd number. The thickness of a piece of 80gsm paper is 0.065 mm, so maybe what is meant is "about the thickness of ten sheets of paper"...?

It's precisely 0.025 inches.

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#126

Post by speg »

marze wrote: post #21

I think if you asked the engineers who designed the airbus in question, could you create a "leak" warning, using just the existing sensor suite, they'd say "sure". You know the fuel level in each tank, and have a good estimate or actual flow data on engine fuel usage. Simple math says "leak" or "no leak". If that would work, it is surprising it isn't in the software.

Isn’t that what they added, from the article:

> Meanwhile, Airbus and the French Directorate General of Civil Aviation worked together to produce a recommended service bulletin modifying the Flight Warning Computers on A330 and A340 aircraft, allowing them to warn of possible fuel leaks by continuously comparing the planned fuel with the actual fuel on board.

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#127

Post by tlb »

cjrp wrote: post #30
tlb wrote: post #27

Earlier quoted context omitted.

Garmin G1000 units (popular in small planes) show this, as a circle around the current position, including fuel reserve. However, it depends on an accurate fuel level, which is mostly dead-reckoned from integrating fuel consumption. Measuring the actual fuel level in wing tanks is imprecise and the sensors sometimes get stuck and give bogus readings. Perhaps the big innovation needed is accurate fuel quantity measure…

Commercial airliners, and even some GA planes, have an accurate measure of fuel consumed using a fuel flow transducer.

Indeed, but that system will report nothing unusual when there's a leak directly from the tank, or in the pipe between tank and flow sensor (which I think is usually near the engine, downstream of a fuel pump) or if the tank wasn't filled to spec.

Any sensor has a failure rate. If the probability that a sensor has failed isn't dramatically lower than the probability of a leak, then the pilots will do just what they did in the incident and assume a bad fuel sensor reading rather than a leak.

Another failure mode of fuel tank sensors is short-circuiting and blowing up the plane: https://en.wikipedia.org/wiki/TWA_Flight_800

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#128

Post by kqr »

dkarl wrote: post #119
mannykannot wrote: post #103

Earlier quoted context omitted.

In this case, there is no evidence here of any ontoward pressure on the maintenance crew, and there is not even any evidence that anyone in the chain of command outside of those involved in the task had any inkling that this might develop into a schedule disruption. On the contrary, the evidence strongly suggests that the maintenance crew did not feel they were under any special pressure: in their minds, they had fou…

This reminds me of times in the first couple of years of my career, where me and some other junior people were terrified that we weren't going to get a project done on time. We would be wracking our brains for out-of-the-box ways to get it done, whispering to each other, having trouble sleeping, and then we would be amazed that the lead developer would simply go to our manager (while we were still desperately brainst…

"It's not management's fault because engineers should expect to and put up with managers treating them harshly (yelling, shaming) when they are doing the right thing"?

Is this really the defense we're using?

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#129

Post by Reason077 »

IIsi50MHz wrote: post #120
Reason077 wrote: post #12

Earlier quoted context omitted.

> ”It's up to you to filter out content you dislike” YouTube’s algorithm is pretty good at doing this for you!

Er, at doing the inverse, for me. "Oh, you're watching a video on foo? Here's a list of video clickbait trash, with sometimes one more video on foo thrown in. "Oh, you either never open or always bail out of 'shorts'? Here are more of them!"

Are you actually signed in? I get all the trash if I'm using anonymous browsing or whatever, but not when it knows who I am.

The "Shorts" section can be hidden pretty easily.

Re: Crisis over The Atlantic: The near crash of Air Transat flight 236

#130

Post by marze »

speg wrote: post #126
marze wrote: post #21

I think if you asked the engineers who designed the airbus in question, could you create a "leak" warning, using just the existing sensor suite, they'd say "sure". You know the fuel level in each tank, and have a good estimate or actual flow data on engine fuel usage. Simple math says "leak" or "no leak". If that would work, it is surprising it isn't in the software.

Isn’t that what they added, from the article: > Meanwhile, Airbus and the French Directorate General of Civil Aviation worked together to produce a recommended service bulletin modifying the Flight Warning Computers on A330 and A340 aircraft, allowing them to warn of possible fuel leaks by continuously comparing the planned fuel with the actual fuel on board.

Missed that. I wonder if it is implemented now.
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