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

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#71

Post by dmead » Wed, Jan 30, 2019, 5:25 PM UTC

ravingraven wrote: post #62

emiliobumachar wrote: post #45

Earlier quoted context omitted.

A tough call. Your solution would disappoint a pilot who actually wanted to slow down ASAP more than Boeing's solution, and might contribute to a runway overrun.

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…

hundreds of people are going to die.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#72

Post by rpeden » Wed, Jan 30, 2019, 5:25 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.

Airbus has been been doing "codeless" development with Esterel products for quite a while. I put codeless in quotes, because I believe the tools to generate code at the end of the day - but it's not code that is written by humans, and it is generated based on formally verified models.

I believe this is what Airbus uses: http://www.esterel-technologies.com/products/scade-suite/

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#73

Post by jagger27 » Wed, Jan 30, 2019, 5:25 PM UTC

ravingraven wrote: post #62

emiliobumachar wrote: post #45

Earlier quoted context omitted.

A tough call. Your solution would disappoint a pilot who actually wanted to slow down ASAP more than Boeing's solution, and might contribute to a runway overrun.

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?

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#74

Post by metalliqaz » Wed, Jan 30, 2019, 5:26 PM UTC

cm2187 wrote: post #66

seiferteric wrote: post #54

Earlier quoted context omitted.

Your forgetting that the cool dense intake air is expanded (greatly) in the engine via combustion with fuel, so the volume of air being exhausted is much greater than went in and at much higher pressure, this is where the thrust comes from in the first place. It's not just a big fan :)

But is it the hot air out of the engine being reversed or the air from the big fan? I thought it was the latter.

It's mostly bypass air.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#75

Post by metalliqaz » Wed, Jan 30, 2019, 5:27 PM UTC

leowoo91 wrote: post #39

Well, Rolls Royce monitors those engines remotely and have access to their logs afaik. So, it should be clear by now whether it has been called from software or not.

That's not true. A full investigation will be required to reconstruct events from all data stored by the various Aircraft systems, including the engines.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#76

Post by _davebennett » Wed, Jan 30, 2019, 5:27 PM UTC

russellbeattie wrote: post #68

I would bet this is going to get a lot more common as a whole generation of heads-down nerdy programmers who got into the industry because of sheer geek joy get replaced by Stack Overflow copy/paste Uber brogrammers who are just looking for a paycheck to fund their weekends in Tahoe. I mean, that's OK and all, but they need to stick to making Fyre apps that crush it by changing the world through social influencers or…

Interesting perspective

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#77

Post by dmead » Wed, Jan 30, 2019, 5:28 PM UTC

anonu wrote: post #48

laretluval wrote: post #2

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

I think software has existed in computer systems for 7 or 8 decades now - and the pitfalls are well understood. I think the problem is one of simplicity vs complexity. New systems today rely on dozens - hundreds even - of packages and libraries - many of which are not written by the implementer. How can you ensure reliability in all these components? This is why engineering from first principles - even in today's sof…

you would be wrong.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#78

Post by AnimalMuppet » Wed, Jan 30, 2019, 5:28 PM UTC

laretluval wrote: post #2

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

The trend over the last 20 years has been that 1: airliners are getting safer and safer and 2: airliners contain more and more software. True, the software introduces new failure modes. But the presence of software in airliners seems to be less a liability than the absence of software.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#79

Post by metalliqaz » Wed, Jan 30, 2019, 5:29 PM UTC

russellbeattie wrote: post #68

I would bet this is going to get a lot more common as a whole generation of heads-down nerdy programmers who got into the industry because of sheer geek joy get replaced by Stack Overflow copy/paste Uber brogrammers who are just looking for a paycheck to fund their weekends in Tahoe. I mean, that's OK and all, but they need to stick to making Fyre apps that crush it by changing the world through social influencers or…

This comment is ignorant as shit. Critical aircraft systems are certified Design Assurance Level A. Programmers are one small part of the development cycle. Every line of code is reviewed, validated, and verified.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#80

Post by bunderbunder » Wed, Jan 30, 2019, 5:29 PM UTC

dajohnson89 wrote: post #33

chrisper wrote: post #24

Earlier quoted context omitted.

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.

There is a notion of blame wrapped up with "too quickly".

I'm having a hard time thinking up an alternative choice of words that is similarly clear and concise.

I also think that the phrase "too X" is polysemous. Depending on how it's used, it may imply a notion of blame. But it can also just be a way of describing an incompatibility. "This clearance is too low for that truck" and "This truck is too tall for that clearance" are entirely equivalent statements, IMO. Neither implies that the truck or the bridge is wrong, just that the driver would be wrong to try and drive under it.

Even further out there, when describing a timing-based bug that isn't known to be 100% deterministic as, "If X is happens too quickly after Y, Z might happen" seems to me like it's just a much more straightforward way of saying, "If X happens within some unspecified interval after Y, then Z might happen." Nine syllables shorter, same meaning.