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Boeing 787 Suffers Rare Dual Engine Failure on Landing

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Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#211

Post by marcosdumay »

phkahler wrote: post #126
eganist wrote: post #36

Earlier quoted context omitted.

There's a further implication that an instruction, but not a failsafe, exists to prevent the given condition. E.g. "do not reverse thrust until ground mode has fully activated." but no check to actually prevent the crew from doing so. I'm not a lawyer; couldn't tell you where the fault would split in that case, but if my hunch about the lack of a failsafe for a given instruction is correct... it's still a surprise to…

>> I'd expect existing avionics production procedures to catch this sort of thing. The older I get, the more I believe your expectation is wrong. Lessons learned are rarely transferred to new people who were not present when the lesson was initially learned. I've even worked at companies that try to compile a database of "lessons learned", but they never instruct anyone to read through the whole thing. Even if they d…

In software, we usually encode lessons learned as tests and static analysis. There is a reasonable level of success on that.

Aviation usually encode them on checklists. They have a much higher degree of success (probably because of culture, not medium), but failures happen some times too.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#212

Post by Retric »

jlg23 wrote: post #188
Retric wrote: post #158

Earlier quoted context omitted.

Is that from other experts with a very close understanding of the specifics, or random people online? What I find is you start with several viable approaches, pick one and go down the path enough to figure out the downsides. At which point you need to decide to backtrack or keep going. That’s the hard part not simply coming up with a seemingly simple solution.

> Is that from other experts with a very close understanding of the specifics, or random people online? These groups are not mutually exclusive, membership can only be assigned by a domain expert and is finally irrelevant if the other is right.

Constraints define good decisions. A new team member making a viable suggestion is very different from a random person tossing out a wild ass guess that happens to be right. The difference is the random commentator has no real way to judge how viable something is, and thus is simply tossing out ideas.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#213

Post by goodcanadian »

stephenr wrote: post #94

Did anyone else find it odd that it took 40 minutes to get the plane towed back to the terminal?

No, not really. It's not an emergency response. They probably did not request it right away as they expected to restart the engines. Once it was requested, they had to find someone available to operate it who had to go get it, perhaps check the fuel and fluids, et cetera, et cetera. Depending on the details, 40 minutes could actually be considered quite quick.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#214

Post by marcosdumay »

Someone wrote: post #63
sschueller wrote: post #6

"Boeing said that selecting full reverse too quickly upon landing before the aircraft has fully transitioned to ground mode could cause the system to activate." That sounds like apple's "you are holding it wrong" when "antenagate" happened. Not something I want to hear from an aircraft company where people's lives depend on it working.

Reading between the lines, and having read other comments here, I can interpret Boeing’s remark as “if the pilots or the on-board software try to reverse engines when it still is really, really dangerous, the Thrust Control Malfunction Accommodation system (TCMA) will try to make matters less bad, in some cases by shutting down the engines instead” . They may have to fine-tune that system, but from a safety perspecti…

> when it still is really, really dangerous

More apt would be "when the computer is not sure that isn't really, really dangerous".

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#215

Post by DuskStar »

detaro wrote: post #97
laken wrote: post #87

Earlier quoted context omitted.

Quoting from the same comment you just replied to: > "On 28 November, Indonesia investigators said the Lion Air jet was not airworthy on flight before crash." "not airworthy" means that it was unsafe.

on flight before the crash . After which it was repaired, and sent on the fatal flight.

It was also repaired before the previous flight.

It goes like this:

several flights report problem

maintenance "fixes" the problem

next flight reports that another, worse problem has appeared - bad enough that regulators have now said that the plane was "not airworthy" during this flight

maintenance "fixes" the problem

final flight impacts ocean at high speed

Your assertion is that since maintenance cleared the plane after the second fix, the plane must have been fine. To that, I point to the previous time maintenance cleared the plane, when it was demonstrably not fine.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#216

Post by bobowzki »

focom wrote: post #200
esemor wrote: post #189

I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…

There is Airplane pilot on HN? I am surprised, did you make a career switch from IT?

I'm always amazed how diverse the people on HN are. Not everyone is an IT professional but we share a passion for technology.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#217

Post by handedness »

jshap70 wrote: post #202
esemor wrote: post #189

I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…

there's a really interesting story around Lauda Air flight 004 where Boeing attempted to write it off as pilot error but Niki Lauda basically threatened to go fly one himself and recreate the conditions as proof it was not. Eventually Boeing conceded and he didn't have to actually risk himself or another of his planes, but still an interesting anecdote.

https://en.wikipedia.org/wiki/Lauda_Air_Flight_004#Niki_Laud...

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#218

Post by dullgiulio »

SomeHacker44 wrote: post #180
ChuckMcM wrote: post #132

Earlier quoted context omitted.

Reminds me of the quote, "For every complex problem there is an answer that is clear, simple, and wrong." -- H.L. Mencken One of the things I have experienced in my career is the mind boggling complexity of the software in systems that are capable of killing people. The more people it can kill the more complex the software. As a result when I read articles like the one posted I find it tantalizing to speculate about…

Yes, Boeing still puts the RAT - ram-air turbine - electrical backup system on their planes.

Why "still"? Even if the chances of a failure of both engines is almost zero, it has happened that there are losses of fuel. The ram-air turbine allows the pilots to have some instrumentation. That's super useful, for example in this accident: https://en.wikipedia.org/wiki/Air_Transat_Flight_236

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#219

Post by frogpelt »

NAHWheatCracker wrote: post #209
t0mas88 wrote: post #142

Earlier quoted context omitted.

It's not very typical for pilots to push buttons quickly. Especially not the thrustreversers and engine and flight controls. But it is entirely possible that nobody pulled the reversers while still airborne in 9 years, because it's a very strange thing to do. A bit like opening your car door while still driving 60 mph... Nobody does that in normal operation.

A bit like opening your car door while still driving 60 mph... Nobody does that in normal operation. You don't open and shut a door when you notice it didn't fully close because you can hear the wind?

A better comparison might be putting the car in reverse at 60 MPH.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#220

Post by sandov »

focom wrote: post #200
esemor wrote: post #189

I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…

There is Airplane pilot on HN? I am surprised, did you make a career switch from IT?

"Hacker: A person who delights in having an intimate understanding of the internal workings of a system [...]"
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