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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

#51

Post by [deleted] »

PhantomGremlin wrote: post #37
jsmthrowaway wrote: post #35

Earlier quoted context omitted.

The computer worked to prevent the aircraft from entering an overspeed condition by pitching up and attempting to recover from the dive even before that dual stick input was an issue. It was intervening 13 seconds into the incident, as the aircraft threatened to exceed safety tolerances. The dual stick input created another issue after that intervention began. The automation very possibly saved lives here. The oversp…

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.

[deleted]

Re: A330 flight control laws saved Voyager, inquiry finds

#52

Post by rtkwe »

Shivetya wrote: post #3

I do not understand, it took only one input to put it in a dive with auto pilot engaged but two inputs to cancel auto pilot to get it out of the dive?

Generally one pilot would just be working the controls and needs to be able to override the auto-pilot in an emergency very quickly. Then when the co-pilot comes in and pulls his stick back the computer doesn't know which to follow without side stick priority being set (which is normally just equal priority) so it goes back to auto-pilot and pulls out of the dive the captain was ordering with his jammed stick.

Re: A330 flight control laws saved Voyager, inquiry finds

#53

Post by sokoloff »

sk5t wrote: post #13
mikeash wrote: post #9

Earlier quoted context omitted.

Indicated airspeed is based on the force of the oncoming air, and decreases as air gets less dense. There's some altitude where 358kt indicated is Mach 0.9. Edit: before I get more replies attempting to lecture me on how wrong I am, please look up the difference between true airspeed (how fast the air is moving past the airplane) and indicated airspeed (a measurement derived from the difference between static and dyn…

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

Re: A330 flight control laws saved Voyager, inquiry finds

#54

Post by huh333i »

duskwuff wrote: post #39
huh333i wrote: post #34

Earlier quoted context omitted.

I have an A320 type so let me try to guess what happened in the A330. The airbus is... different. You can displace the stick 100% in any direction and it wont bank beyond 67 degrees, pitch up more than 30, or pitch down more than 15. It wont overstress because the stick controls G-forces through a closed feedback loop. It also has high-speed protections where it will automatically apply positive G-force to pitch up i…

> If you get too careless it will even run the engines up to full takeoff thrust and microblog it to you. What does "microblog" mean in this context? I assume it doesn't mean that the A330 isn't posting about its engine thrust on Twitter. (Yet.)

The thrust FMA (flight mode annunciator) will show "A. FLOOR" alpha floor or "TOGA LK" (takeoff/go-around thrust lock). The former means Fifi just took over and is applying full thrust for an immediate high AoA situation. The latter means the emergency is over but Fifi is so white knuckled and panting that she's ignoring lever position and keeping full thrust. I say microblog because you have to make a conscious effort to read these things. I just got curious and did some googling and it I'm not the only one who can be confused... The aural warning for low speed is the last thing you hear and unless you actually see TOGA LK and turn off autothrust you'll be overspeeding soon. With flaps down (lower max speed) this happens pretty fast. https://news.aviation-safety.net/2013/12/21/loss-of-airspeed...

Re: A330 flight control laws saved Voyager, inquiry finds

#55

Post by Filligree »

mikeash wrote: post #41
sk5t wrote: post #21

Earlier quoted context omitted.

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.

I'm not familiar with that one. Does that mean to take 300mg?

I hope so. It sure as hell can't mean 300g, and anything other than mg would be crazy, but I'm not feeling very confident here.

Re: A330 flight control laws saved Voyager, inquiry finds

#56

Post by [deleted] »

sk5t wrote: post #8
sk5t wrote: post #5

> with a maximum indicated air speed of 358kt (662km/h), or Mach 0.9, recorded What? 358 knots is much closer to mach 0.5 in air. 358 meters/second is close... 662 mph is close.

Further confusing numbers: > “Up to 24% of the aircraft occupants were rendered temporarily unfit for duties following the incident,” the report adds, referring to 25 passengers and seven crew members. > “Without the excellent technology of the Airbus A330 flight control laws, the outcome could have been very different, with the realistic potential for the loss of the aircraft and 198 of our people,” MAA director gen…

[deleted]

Re: A330 flight control laws saved Voyager, inquiry finds

#57

Post by werdna123 »

tropo wrote: post #43
jsmthrowaway wrote: post #35

Earlier quoted context omitted.

The computer worked to prevent the aircraft from entering an overspeed condition by pitching up and attempting to recover from the dive even before that dual stick input was an issue. It was intervening 13 seconds into the incident, as the aircraft threatened to exceed safety tolerances. The dual stick input created another issue after that intervention began. The automation very possibly saved lives here. The oversp…

Nope, it wouldn't happen in a Boeing aircraft. This is a well-known Airbus defect that was a contributing factor to the crash of Air France Flight 447. Boeing uses traditional controls. It's like a race car steering wheel on a big movable stick. It is really easy to see how the control is positioned. Airbus uses a small joystick off to the side. It is force-based like a Thinkpad pointing stick, so it barely moves whe…

Yep, partisanship aside, the side-stick design is dangerous as seen here and the Air France disaster.

Re: A330 flight control laws saved Voyager, inquiry finds

#58

Post by Dylan16807 »

NamTaf wrote: post #44
sk5t wrote: post #21

Earlier quoted context omitted.

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.

Why? Do you take issue to the fact that scales show you a measurement in kg rather than N despite it varying as you move around the world (and potentially with changes in temperature, depending on the type of scales)? Velocity/mass is far more intuitive than pressure/force even if they don't apply exactly the same in all cases. It's about what works easiest for the users of the system.

kg/N varies, but by less than your normal margin of error. That's vastly different from deciding to use newtons to weigh "kilograms indicated" on your trip to mars when they give a vastly different number.

Re: A330 flight control laws saved Voyager, inquiry finds

#59

Post by Pxtl »

JBReefer wrote: post #48
1_2__3 wrote: post #47

Earlier quoted context omitted.

There were only 25 passengers...

The article states there was 198 souls on board

The article is confusingly worded, mentioning 25 passengers and 7 crew in another part... Which are also described as 25% of occupants, but that's not 25% of 198.
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