Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Boeing 787 Suffers Rare Dual Engine Failure on Landing

thepointsguy.com

Post reply on HN
Print view View original

111–120 of 365 posts

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#111

Post by ravingraven »

jagger27 wrote: post #73
ravingraven wrote: post #62

Earlier quoted context omitted.

No, it would not. If the engine is shut down moments before touching down it would mean that there would be no reverse thrust after touching down since it takes a considerable amount of time to re-start a turbo-fan (not 60 seconds as OP wrote as the engine is still spooling but still a significant amount of time and I don't think that any pilot would go through the workload and checklists of re-starting an engine dur…

> or to only engage reverse thrust once the landing gear has weight on it. Having reverse thrust depend on a sensor that could fail seems like a poor choice. What if the landing gear don't drop? Is there a situation where you would still want reverse thrust without landing gear?

Most things in aircraft automation systems depend on sensors that could fail (those sensors could be redundant etc. but the same can be done with the sensors on landing gears). It is sane design.

> What if the landing gear don't drop?

I don't think that there is need for reverse thrust in such a scenario.

> Is there a situation where you would still want reverse thrust without landing gear?

Even if there is, there could be a manual override.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#112

Post by maxxxxx »

nck4222 wrote: post #110
code4tee wrote: post #19

Boeing’s answer seems to say if you accidentally pull the thrust reverser lever before the aircraft is on the ground it just force shuts down the engines. That sounds like an odd safety override. Surely a better solution would be to just not activate reverse thrust. Unlike car engines a jet engine can’t just be quickly restarted if it accidentally shuts down. It typically takes 30-60 seconds to get going. This and ea…

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#113

Post by danielvf »

IshKebab wrote: post #106
Mithorium wrote: post #58

Earlier quoted context omitted.

To save people the reading, the safety feature triggered was an automatic dive maneuver initiated by the flight computer as a result of an incorrect angle-of-attack sensor reading causing the plane to believe it was in a stall, when it actually wasn't I didn't look into it any further, but based on that alone I would agree that this seems like a shitty feature, perhaps a loud alarm or other warning would be more appr…

A big issue with that flash was that there was a way to disable the feature, but Boeing didn't tell anyone about it and it wasn't documented anywhere.

You can still disable the stabilizer trim from switches in the cockpit, though. This was in the checklists that the pilots had, and done by other pilots in that aircraft in the days before the accident.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#114

Post by cm2187 »

metalliqaz wrote: post #70
cm2187 wrote: post #50

Earlier quoted context omitted.

I thought that most modern aircrafts were not allowing the reverse to be deployed if the wheels didn't touch the runway. Talking about an odd safety override. It's kind of a self-destruct button.

It's not an odd safety override. An overthrust situation is always dangerous for various reasons. One of the more spectacular is the possibility of liberating airfoils from the engine and shooting them into the cabin. It's not a self-destruct button, it's anti-destruct limit. As for the thrust reverser, there are many integrated systems on the aircraft. It's possible that the cockpit detected weight-on-wheels, but th…

By self destruct, I meant switching off the engines in flight seems to me to be a terribly dangerous behavior.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#115

Post by markholmes »

maxxxxx wrote: post #112
nck4222 wrote: post #110

Earlier quoted context omitted.

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

In this case, possibly years

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#116

Post by ergothus »

maxxxxx wrote: post #112
nck4222 wrote: post #110

Earlier quoted context omitted.

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

It's worse when they are right though. I wish I could say that had not happened to me.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#117

Post by Xcelerate »

maxxxxx wrote: post #112
nck4222 wrote: post #110

Earlier quoted context omitted.

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

I always appreciate those comments. Sometimes they include something obvious I never thought of.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#119

Post by 4thaccount »

maxxxxx wrote: post #112
nck4222 wrote: post #110

Earlier quoted context omitted.

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

I found that I now distrust a lot of articles as people tend to get the things in my field blatantly wrong all the time.

Things are complicated and rarely as simple as they seem.

On the other hand, I've worked on things for hours before for someone to glance at the problem and solve it. Always a humbling experience.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#120

Post by ricardobeat »

maxxxxx wrote: post #112
nck4222 wrote: post #110

Earlier quoted context omitted.

Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…

I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".

They are right more often than you’d expect. Irrational escalation, loss aversion, confirmation bias, etc play their part everywhere causing senseless projects to be pushed to completion.
Post reply on HN