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A330 flight control laws saved Voyager, inquiry finds

flightglobal.com

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Re: A330 flight control laws saved Voyager, inquiry finds

#71

Post by brandmeyer »

sk5t wrote: post #21
mikeash wrote: post #18

Earlier quoted context omitted.

It literally says "indicated air speed." There's no need for interpretation or assumption. If I saw a raw airspeed without and qualifier, I'd probably assume it meant indicated speed. But I fly small planes where that's the only airspeed available. If you want true airspeed, you have to take what's indicated and convert manually.

So it does. I still find this disunion of UOM disagreeable, in the way that "in thousandths, take 300 grams of acetaminophen twice daily" is troubling.

The aircraft has a maximum speed rating, beyond which the structure may fail. That speed rating is based on the aerodynamic forces on the aircraft, which are proportional to the indicated airspeed, not the true airspeed. That's why the instrument panel almost universally shows IAS. That way the pilot doesn't need to perform an altitude-based nonlinear conversion in his head during an emergency to see that he's about to kill everyone on board.

Re: A330 flight control laws saved Voyager, inquiry finds

#73

Post by mikekchar »

JshWright wrote: post #68
PhantomGremlin wrote: post #37

Earlier quoted context omitted.

A Boeing would not have intervened in the situation at all OTOH it's probably a lot harder to "jam" a camera into the center stick of a Boeing than it is into the side-stick of a Bus.

The biggest advantage of the Boeing approach is that the controls are linked; if one moves, so does the other. Mismatched inputs are impossible. I truly don't understand the Airbus approach... There is no method of resolving conflicts between the sticks that make sense... Sum them? Average them? Take the last seen input? Prefer the left side always?

Not knowing anything about it, it seemed to me from the article that the system takes mismatched input as an indication that the autonomous systems need to be engaged. Though if it subsequently decides not to engage, I'm not sure what you should do...

Re: A330 flight control laws saved Voyager, inquiry finds

#74

Post by 6stringmerc »

After reading the summary it sounds like a "CAPTAIN HAD A MASSIVE HEART FAILURE AND SLUMPED FORWARD ON THE CONTROLS DO NOT CRASH AIRPLANE FROM CRUISE ALTITUDE IF POSSIBLE" which might sound pretty obvious but, uhh, that's some nice code work. That's why there are two (2) pilots in theory/practice, because human redundancy is a valuable asset.

I can't help but think if there was a video camera in the cockpit it might have looked a lot like that scene in "The Big Lebowski" where he drops his joint between his legs while driving and then loses control and hits a dumpster. Shit tends to domino from time to time lol.

Re: A330 flight control laws saved Voyager, inquiry finds

#75

Post by fryguy »

m_mueller wrote: post #63

> "Up to 24% of the aircraft occupants were rendered temporarily unfit for duties following the incident" Gotta love the officialese for 'people puked everywhere'....

Or flung into the ceiling headfirst at 0.5g and then back to the floor at 2g. Presumably that could cause injuries other than motion sickness.

Re: A330 flight control laws saved Voyager, inquiry finds

#76

Post by ririau »

6stringmerc wrote: post #74

After reading the summary it sounds like a "CAPTAIN HAD A MASSIVE HEART FAILURE AND SLUMPED FORWARD ON THE CONTROLS DO NOT CRASH AIRPLANE FROM CRUISE ALTITUDE IF POSSIBLE" which might sound pretty obvious but, uhh, that's some nice code work. That's why there are two (2) pilots in theory/practice, because human redundancy is a valuable asset. I can't help but think if there was a video camera in the cockpit it might…

Remember that most of the sources of typical crashes or problems have been eliminated. Which means that accidents happen they're always freak accidents.

Re: A330 flight control laws saved Voyager, inquiry finds

#77

Post by fryguy »

JshWright wrote: post #68
PhantomGremlin wrote: post #37

Earlier quoted context omitted.

A Boeing would not have intervened in the situation at all OTOH it's probably a lot harder to "jam" a camera into the center stick of a Boeing than it is into the side-stick of a Bus.

The biggest advantage of the Boeing approach is that the controls are linked; if one moves, so does the other. Mismatched inputs are impossible. I truly don't understand the Airbus approach... There is no method of resolving conflicts between the sticks that make sense... Sum them? Average them? Take the last seen input? Prefer the left side always?

I don't work in avionics, but in another field with two pilots. Most things are done by exclusive control meaning there is a selector for which station has the flight stick. But for shared control the way it works is the first station that has non-zero inputs takes exclusive control until they have zero inputs for a short period of time. Although in our case, the availability of two sticks is for hardware redundancy rather than pilot redundancy so the Boeing approach seems safer.

Re: A330 flight control laws saved Voyager, inquiry finds

#78

Post by sk5t »

sokoloff wrote: post #53
sk5t wrote: post #13

Earlier quoted context omitted.

Thanks for the clarification. Is it normal to refer to kts with the assumption this is related to pressure on the airframe and not actual airspeed? The reference to the 365KIAS rating later in the article provides only a clue IMO.

"KIAS" is literally "knots indicated air speed" "KTAS" would be "knots true air speed" It's no more a clue than "mph" would be a clue for "miles per hour", IMO

Yes, my suggestion is that KIAS is an okay UOM, and knots is inappropriate/confusing.

However, unlike the xkcd strip about HO model trains, I'm not ready to mount a ferocious defense with regard to this thing I just heard about.

Re: A330 flight control laws saved Voyager, inquiry finds

#80

Post by 6stringmerc »

ririau wrote: post #76
6stringmerc wrote: post #74

After reading the summary it sounds like a "CAPTAIN HAD A MASSIVE HEART FAILURE AND SLUMPED FORWARD ON THE CONTROLS DO NOT CRASH AIRPLANE FROM CRUISE ALTITUDE IF POSSIBLE" which might sound pretty obvious but, uhh, that's some nice code work. That's why there are two (2) pilots in theory/practice, because human redundancy is a valuable asset. I can't help but think if there was a video camera in the cockpit it might…

Remember that most of the sources of typical crashes or problems have been eliminated. Which means that accidents happen they're always freak accidents.

Not really, that recent crash in San Francisco had alarms going off like crazy and the idiot pilot still managed to crash the plane. Once you read enough NTSB reports / bulletins about General Aviation accidents (usually only big stuff makes the news) it becomes very clear that accidents happen and bad decisions happen. Like turning off the wrong engine...
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