Boeing 787 Suffers Rare Dual Engine Failure on Landing • Hacker News Board

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#21

Post by cpcallen » Wed, Jan 30, 2019, 4:45 PM UTC

minedwiz wrote: post #17

exabrial wrote: post #12

Sort of off topic, but reverse thrust sort of boggles my mind. If you're sucking air in from the front of the aircraft and ejecting it out the front, don't those forces counterbalance each other?

Reverse thrust doesn't come directly out the front of the engine - it's vented out the side (or, in very old engines, redirected from the back exhaust): https://upload.wikimedia.org/wikipedia/commons/d/df/F-GTAR_A...

That makes it even more surprisingly counterintuitive.

I think the important thing to consider is the relative velocities of the intake and exhaust air (the latter being much larger).

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#22

Post by doctoring » Wed, Jan 30, 2019, 4:45 PM UTC

deugtniet wrote: post #10

Is there something special about the software in new Boeings? Dual engine failure is nothing to sneeze at, and should never happen. Airbus also had its fair share of software errors in history, but if we count the recent Lion air crash as software related, Boeing has had 2 serious software related incidents in a year and I haven't heard anything serious from airbus. Is it because Airbus started its fly-by-wire develo…

I think with these types of incidents being very rare, it's hard to extrapolate to any kind of patterns.

Not within the year, and I'm sure there are more (for both Boeing and Airbus), but this one comes to mind on an Airbus that's pretty scary -- thankfully occurred at cruising altitude: https://en.wikipedia.org/wiki/Qantas_Flight_72

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#23

Post by gedy » Wed, Jan 30, 2019, 4:47 PM UTC

minedwiz wrote: post #8

laretluval wrote: post #2

I hope people are beginning to understand that the presence of software in any system is a liability.

Boeing 777 is also digital fly-by-wire and has never suffered an issue attributable to software error.

"Well, I don’t think there is any question about it. It can only be attributable to human error."

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#24

Post by chrisper » Wed, Jan 30, 2019, 4:47 PM UTC

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.

It doesn't at all. It's an explanation why it might happen.They never said that this behavior won't be fixed or changed. It's not blaming the pilots.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#25

Post by [deleted] » Wed, Jan 30, 2019, 4:47 PM UTC

exabrial wrote: post #12

Sort of off topic, but reverse thrust sort of boggles my mind. If you're sucking air in from the front of the aircraft and ejecting it out the front, don't those forces counterbalance each other?

[deleted]

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#26

Post by mikeash » Wed, Jan 30, 2019, 4:48 PM UTC

onewhonknocks wrote: post #4

I'm not sure this is a bug. It sounds like pilot-error to me (I am not a pilot): "In the bulletin, 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."

Pilot error happens and the equipment is expected to make it as difficult as possible. If a simple action can endanger a plane-load of passengers, that’s a bug regardless of whether the pilot is supposed to do that.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#27

Post by lsllc » Wed, Jan 30, 2019, 4:48 PM UTC

glup wrote: post #9

laretluval wrote: post #2

I hope people are beginning to understand that the presence of software in any system is a liability.

After serverless comes codeless.

"low code" is a thing apparently.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#28

Post by Mvandenbergh » Wed, Jan 30, 2019, 4:49 PM UTC

onewhonknocks wrote: post #4

I'm not sure this is a bug. It sounds like pilot-error to me (I am not a pilot): "In the bulletin, 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."

The aviation safety world doesn't believe in pilot-error.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#29

Post by abfan1127 » Wed, Jan 30, 2019, 4:49 PM UTC

mikeash wrote: post #20

Jhndb wrote: post #14

Earlier quoted context omitted.

Going off your quote it just looks like they're describing the symptom?

It’s a completely neutral statement, and air travel has a strong culture of not accepting “just don’t screw up” as a solution.

Airbus has a limitation on one of their airplanes for Rudder Range - https://www.usatoday.com/story/travel/flights/2012/11/19/air...

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#30

Post by danielvf » Wed, Jan 30, 2019, 4:49 PM UTC

aaronbrethorst wrote: post #5

nitinreddy88 wrote: post #3

How many easter eggs will emerge from Boeing. In last 2 months, we had similar incidents from Boeing where an undocumented software safety kicked in and causing trouble for everyone

and causing trouble for everyone You mean killed 189 people, right? https://en.wikipedia.org/wiki/Lion_Air_Flight_610

That aircraft was being knowingly flown with [edit: a broken sensor]. It was unsafe on takeoff.

The final problem that brought the aircraft down - the trim run-away - happens all the time in airliners you've flown in. When the run-away starts, the pilot is supposed to flip two switches to disable the trim system motors. In the Lion Air crash, it is indeed believed that a software bug from the misbehaving sensors started the run-away, but again, handling trim run-aways are something that pilots are supposed to train for and deal with.

737's are even safer here than many airliners, because after you disable the electric trim motors, you have manual wheels in the cockpit that you can rotate to set the trim back to what it should be. Some other airliners in common use don't have these manual trim controls - you have to disable a trim run-away in time, or it's game over.