General > General Technical Chat

don't forget to reboot your boeing, or else

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MK14:

--- Quote from: coppercone2 on April 04, 2020, 02:53:57 am ---it just could be a sum of data samples that fills up a memory space from multiple sensors or something (does not make sense to sample some sensors at ultra high frequencies probably). Maybe it makes a SOA from different sensors data inputs.

--- End quote ---

(To avoid confusion, I'm NOT attacking your post. Just describing the difficulty of trying to determine someone else's mistake/bug, when the full information is apparently not available).
Yes, we could speculate, on the millions of ways, they could have messed up. But, it is like finding a needle in a haystack.

Although I've not seen the precise details. There is some details on the specifics of the bug, floating around.


--- Quote ---the 787's common core system (CCS) stops filtering out stale data from key flight control displays. That stale data-monitoring function going down in turn "could lead to undetected or unannunciated loss of common data network (CDN) message age validation, combined with a CDN switch failure".
--- End quote ---

https://www.theregister.co.uk/2020/04/02/boeing_787_power_cycle_51_days_stale_data/

duak:
One company I worked at had a number of aviation buffs.  One of them said something interesting about passenger aircraft - I don't know if it's factually true or just truthy.  He said that McDonnell-Douglas had two hydraulic systems, Lockheed had three and Boeing had four.  This happened at a time when M-D had a number of spectacular failures in the DC-10.  BTW, he worked for McDonnell before they were merged with Douglas.  This probably contributed to me being more confident in Boeing.

I've flown about 75 times domestically and overseas over the years.  The most exciting mechanical failure was a hydraulic system crapout in a Fokker.  The crew had to crank down the gear, and we circled until the emergency team got in place.  It took a bit longer to come to a stop but if you didn't know something was up, you'd wonder what they were worried about.  It was much more exciting to land in Jakarta, Indonesia during a thunderstorm in a DC-10 or the dogleg final approach at Hong Kong's old Kai Tak airport in a 747.  A crosswind landing at SFO will also wake you up.  I don't recall having been in a missed approach.

In 1997, my wife and I flew from Seattle to LAX in a newish Alaskan Airlines 737.  We were cleared to go, the engines spooled up then just spooled down.  No bangs or funny noises.  A few seconds later the engines spooled up then just spooled down again.  Then a long pregnant pause before the captain came on and said we'd head back to the gate.  About an hour later, the captain came on and said the tech had reset the computer a few times but still had a problem so the computer was changed out.   I remember something a colleague said when asked why he didn't like to fly.  "Planes have computers with firmware in them".  BTW, both he and I designed hardware and wrote the firmware.  I suppose I was thinking about the fallibility of computers and whether this was a warning to get off the aircraft.  The flight was uneventful, but I wouldn't have been surprised if the engines decided to spool down and we had to glide in somewhere - assuming nothing else developed.  Fly by wire indeed!

SiliconWizard:
Whatever the technical reason at the implementation level, what is concerning IMO is that it never got caught during any test; either that, or it was actually specified this way, or not specified at all.

So we can debate/guess internal counter widths or buffer sizes to no end, but the specification, verification and/or validation stage clearly failed somewhere.

JustMeHere:

--- Quote from: MathWizard on April 04, 2020, 03:06:12 am ---Boeing, what an enigma. They make bombs to kill 3rd world people, to help make rich people richer, and they make nice planes, overall.

--- End quote ---

Boeing has never made a bomb.

Kilrah:
Again? They got another issue of the same type back in 2015... https://www.theregister.co.uk/2015/05/01/787_software_bug_can_shut_down_planes_generators/

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