8 ms·
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
by esemor 8y ago
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) but as it is a catastrophic failure, having the engine shut down automatically seems like a great fail safe device.
In this case it seems that the 787 engines were reversed before the air/ground sensor had sensed ground and it is a potential problem.
- focom 8y agoThere is Airplane pilot on HN? I am surprised, did you make a career switch from IT?
- sandov 8y ago"Hacker: A person who delights in having an intimate understanding of the internal workings of a system [...]"
- bobowzki 8y agoI'm always amazed how diverse the people on HN are. Not everyone is an IT professional but we share a passion for technology.
- newnewpdro 8y ago'Passionate' is not the adjective I would use to describe my feelings towards technology.
- andrewflnr 8y agoMaybe more like passion in the "crime of..." sense?
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- subhro 8y agoAirplane pilot checking in. There are multiple. :)
- astrodust 8y agoModern planes are flying server farms. How is this surprising? I've worked with several pilots in my career. Unless you have a ton of experience, IT pays better than flying.
- Keloo 8y agoYes, some of my software engineer colleagues are pilots as well. You never know who you are talking to, especially now-days.
- deleted 8y ago[deleted]
- jshap70 8y agothere'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.
- handedness 8y agohttps://en.wikipedia.org/wiki/Lauda_Air_Flight_004#Niki_Lauda's_visit_with_Boeing https://en.wikipedia.org/wiki/Lauda_Air_Flight_004#Niki_Laud...
- philjohn 8y agoThat's just the kind of person Lauda is. He was severely burned in a Formula 1 race at the Nurburgring, and despite still suffering badly scarred lungs and weeping wounds he was back in the seat before the end of the season and only lost the championship that year because he refused to go out in the pouring rain to race the Japanese Grand Prix as he decided it would have been foolhardy.
- weaksauce 8y agoit's a great fail safe but not if you lose your engines in flight and can't relight them like in the article.
- bunderbunder 8y agoCutting power to all engines in response to an event that is most likely to happen while the aircraft is operating close to, but not actually on, the ground is not failing safe.
- weaksauce 8y agoI am not sure there is a perfect solution here. you have competing issues that you need to resolve. If it gets pulled in normal flight you would lose both engines but that's fine because you can glide and restart the engines. if the altitude sensor/ground sensor was broken and you want to override the reverse thrusters you have a conflicting goal there. If you accidentally pull it during the approach you lose your engines and probably don't have time to relight before landing. in that case you might be able to still land by backup systems(FAU or just the ancillary tail turbine?) and glide? I guess it boils down to how much trust you place in the pilots to not do the wrong thing or how much trust you place in the machine to not do the wrong thing/malfunction. It's a difficult question without a perfect solution imo.
- deleted 8y ago[deleted]
- bunderbunder 8y agoWell, I thought that the design was that they would not engage if it gets pulled in normal flight. If it's on the approach, I'd be worried. I imagine that that, at an airport like ORD, that might result in more risk than anyone really wants of the plane unexpectedly touching down on an interstate highway or something like that. If it's like what Boeing described in the bulletin, where the engines only get shut down after the wheels are on the ground, that's maybe not super worrisome, but I can still see some room for concern. My reconsidered but still totally uninformed reading on the situation is that it takes some time for all the aircraft's systems to get the memo on whether the plane is on the ground, and that what's really going on here is that the order in which they get the memo isn't quite right. So the question of whether or not to allow a Lauda Air type situation isn't really at play here, but perhaps a related glitch to the one that caused this event could interfere with something like aborting a landing at the last minute.
- slavak 8y agoTCMA, the system the article refers to, doesn't actually shut down the engines in flight. In fact, one of the explicit conditions for its activation is the aircraft being on the ground: > The EEC commands shutdown of the affected engine when the: > • airplane is on the ground, and > • thrust lever is at idle, and > • engine is above idle speed and not decelerating normally > The EICAS caution message ENG FAIL (L or R) is displayed with an aural beeper once the engine falls below idle speed. https://quizlet.com/27148021/engines-apu-787-ge-engine-flash-cards/ https://quizlet.com/27148021/engines-apu-787-ge-engine-flash...
- dorfsmay 8y agoAs long at it is well documented and part of the training, and also ideally the system should indicate to the pilot why it is shutting down the engine(s), to avoid something like this: https://en.wikipedia.org/wiki/TAM_Transportes_A%C3%A9reos_Regionais_Flight_402 https://en.wikipedia.org/wiki/TAM_Transportes_A%C3%A9reos_Re... "The safety system automatically cut the power to the engine suffering the thrust reverser malfunction. There was no alarm in the cockpit to indicate that a thrust reverser had been accidentally deployed. The crew had no way of knowing what the true problem was. The copilot, seeing the right engine power lever automatically move to the closed position, thought that the lever had slipped back and pushed it back to the full power position alongside the left engine throttle lever. Once again, the automatic safety system closed the right engine throttle and the captain, who was conducting the takeoff, called for the autothrottle system to be switched off. After switching off the system, the copilot again pushed the right engine power lever fully forward and forcefully held it there."
- heyjudy 8y agoHmm. There might need for a sooner transition point for that particular inhibition. Perhaps somewhere between ground effect (well below minimums) and back trucks are turning.
- newnewpdro 8y ago> In this case it seems that the 787 engines were reversed before the air/ground sensor had sensed ground and it is a potential problem. What I don't understand is why does the reverse thrust input from the cockpit even influence the engine control when the air/ground sensor doesn't sense ground? It seems like an obvious lockout mechanism to have in place, if the result is shutting down the engines when the combination occurs. Then just have a manual air/ground sensor override should that thing fail and you know you're on the ground and require reverse thrust.
- zepearl 8y agoSummarized, I understand that you mean that a malfunction in the "reverse-thrust-detector" (which switches off automatically the involved engine(s) when the reverse-thrust is not operating within its envelope => referenced as "feature" below) is more desirable than not to have it? (because if, when having a mulfunction of the detector's "feature" in mid-air the engines switch off you still have some time to fix/override it, but on the other hand when not having it if your reverse-thrust engages you're screwed immediately - and even if the feature fails nearby the ground you're still be slow & low enough for at least some passengers to have some chance to survive) Correct?
- esemor 8y agoYes, no engines is bad but thrust reverser in flight is a instant killer.
- l33tman 8y agoApparently it's bad if done at cruise (due to the small margins in thin air) but if done in mid-air it's controllable. See this episode of Mentour Pilot: https://youtu.be/OguKthkuaT4 https://youtu.be/OguKthkuaT4
- alexbanks 8y agoI am very scared of flying (although I still do it, although it's not fun). Any advice/rationalism you can convey? I am a person that became sweaty and anxious reading your post.
- tjohns 8y agoMy advice is to look at the statistics. Commercial flying is much, much safer than any other mode of transport. Do you get scared when you drive to work? Or take a train? Both are more risky. (Driving significantly so.) More specifically... The pilots have extensive training, modern airliners have fail safes everywhere, and the amount of research and engineering spent on aviation safety is mind boggling. See: http://airlines.org/dataset/safety-record-of-u-s-air-carriers/ http://airlines.org/dataset/safety-record-of-u-s-air-carrier...
- soheil 8y agoAn accident during flight is pretty much a binary event when it comes down to whether you live or not, but with cars there is a whole slew of different types of accidents and vast majority of them don't cause instant death preceded by 45 seconds of absolute terror. Before you downvote what I said in no way discounts the statistics. It is much safer to fly of course than to drive, but when we think of accidents which is an inevitable fact of any mode of travel one mode is binary you live or die and another not. To our mammalian brains the statistics is a very hard sell.
- repiret 8y agoI agree with what you say, but I think it has more to do with (perceptions of) control than the failure modes. When you’re in an automobile, you could choose to drive faster or slower, safer or more aggressively. You can tell yourself that you are more alert or a better driver to the people who die in fatal car accidents. You can tell yourself that you have a superior ability to avoid that drunk driver who might suddenly veer into your lane from oncoming traffic. And once your car comes to a stop, if you’re not seriously injured, you can just get up and walk away. In an airplane there’s none of that. You can make vanishingly few choices to affect the safety of your flight. And you’re stuck in that tin can until it’s on the ground and you’re either alive or dead.
- sandworm101 8y agoFyi, military pilot here, there are a handful of mil aircraft that can reverse thrust in flight. A great too for dropping down fast to avoid low/slow flight over hostile areas. There might be a relationship between that ability and this problem.
- grkvlt 8y agoAlso, as I recall, Concorde could do this too...
- esemor 8y agoLucky bastards, get all the fun features...
- sandworm101 8y agoIt can be crazy dangerous. Once a big plane is dropping like a rock, getting back into a climb is very difficult.