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A330 flight control laws saved Voyager, inquiry finds

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Re: A330 flight control laws saved Voyager, inquiry finds

#141

Post by Shivetya »

huh333i wrote: post #34
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?

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…

thank you, you were far more clear than the article

Re: A330 flight control laws saved Voyager, inquiry finds

#142

Post by FabHK »

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?

Of course there is a system, and it's sophisticated. Averages are taken in case of inputs on both, and there's a priority button to take precedence (so that the other is ignored). There's more to it than that, but of course there's a system and a lot of thought has gone into it.

In the AF 447 case, the left pilot did take priority, but the dude on the right took it back. Had the left one taken it and held it (by keeping the button pressed), the accident might have been avoided. So the system is hardly foolproof, and one can argue about the particular implementation of the interface and the merits vis-a-vis hardware-linked yokes, but any notion that Airbus haven't thought carefully about it is complete bogus.

http://aviation.stackexchange.com/questions/3455/why-is-the-...

Re: A330 flight control laws saved Voyager, inquiry finds

#143

Post by DonaldFisk »

mikeash wrote: post #9
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.

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…

Thin and very cold air.

The altitude was 33000 feet (FL330). Assuming a ground temperature of 15 celsius and a drop in temperature of 2 degrees per 1000 feet gives an OAT of -51 celsius. My flight computer converts 358KIAS @ 33000feet @ -51celsius to 620KTAS, which is Mach 0.94.

FL = flight level (hundreds of feet)

KIAS = knots indicated air speed

KTAS = knots true air speed

OAT = outside air temperature

Re: A330 flight control laws saved Voyager, inquiry finds

#144

Post by paulmd »

colanderman wrote: post #69
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.

When coining new terms at my day job (software engineer) I try to avoid terms like "indicated air speed" for the reason that part of the term – "indicated" in this case – is easily ignored by those less familiar with the terminology, because it seems superfluous. (In this case, "indicated" to a layperson simply means "it was shown on a dial". In that interpretation, it carries little information and hence gets ignore…

As a pilot, you cannot escape knowing this terminology. Knowing how your instruments do their measurements ("indicated vs true air speed", among others) is absolutely integral to the job, if you don't want to fly into a formation of "cumulo-granite" somewhere along the line.

One is what your pitot tube is telling you - which is a combination of altitude, weather conditions, wind, and airspeed.

The other is how much air is flowing over your wings - which is what actually keeps you aloft.

To quote the ace fighter pilot Yogi Berra - "In theory, theory and practice are the same. In practice, they are not".

You cannot escape pressure-altitude. It has way more implications than this. Starting with your ability to get off the ground.

Re: A330 flight control laws saved Voyager, inquiry finds

#145

Post by dct »

chanandler_bong wrote: post #19

From the headline, I could not figure out how an A330s flight control system could have any influence on spacecraft launched in 1977. Surely there would be no way to port the code and the storage on the Voyagers is tiny... at least until the V'ger Mk. I upgrade.

Voyager is the name RAF use: http://www.raf.mod.uk/equipment/voyager.cfm

Re: A330 flight control laws saved Voyager, inquiry finds

#146

Post by 6stringmerc »

ldp01 wrote: post #119
wapz wrote: post #86

Earlier quoted context omitted.

Was this the Korean (whichever of the companies) airlines crash? I didn't read up too much into it after the fact.

Taipai, Taiwan. I believe it had trouble in one engine briefly after takeoff, and the pilots tried turning it on and off again. Unfortunately they turned off the still-functioning engine and it plummeted into a river. You might remember the shot of it flying over a bridge, rolled 90 degrees and so close to the ground that the wing partly sheared off.

Yeah originally the news cycle had some spin on it - I clearly remember some lines about "Wow check out the heroic actions by the pilot to avoid crashing into any buildings!" and later when the cockpit recorder came out, uhhh, not so heroic. Human, an error...preventable? Up for debate but I like to think a lot of US regulated pilots would be able to handle it appropriately.

Re: A330 flight control laws saved Voyager, inquiry finds

#147

Post by Declanomous »

CaptainZapp wrote: post #122
closeparen wrote: post #83

Earlier quoted context omitted.

Is it me or has seat-belt-sign discipline gone out the window? Over my December travels, dozens of passengers on all 4 segments I flew openly flaunted the seat-belt sign, getting up to go to the bathroom and standing in the aisle waiting for it in full view of flight attendants, who didn't say anything. I broke down and did so myself, as the seat belt sign was on for the vast majority of the flight and I was getting…

Not really. My observations go for intra-European flights, though. You're usually also not yelled at when queuing for the loo, provided the seat-belt sign is off. What I do notice a lot, though, is passengers that unbuckle half a second after touch down. To me this seems incredibly stupid. For starters: it's really dangerous to them and by extension to their fellow passengers and to emphasize the idiocy: They're off…

I think it's the same mindset of people who wear a seatbelt with the shoulder restraint tucked behind them: "It's uncomfortable! And besides, it only affects me!"

That's great, except that your tubby ass will become a missile if anything happens to this vehicle. Also, planes have a habit of randomly jumping around with no warning because of invisible turbulence.

Re: A330 flight control laws saved Voyager, inquiry finds

#148

Post by Declanomous »

Xixi wrote: post #137
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…

All modern Boeings (>= B777) are FBW (fly by wire) and have flight envelope protection. A 787 will absolutely not go over-speed: it will automatically throttle back.

Also, Boeings have a traditional yoke. It seems like a lot of this trouble was caused by the fact a sidestick can easily be hit by something on the front of the chair.

Re: A330 flight control laws saved Voyager, inquiry finds

#149

Post by [deleted] »

Xixi wrote: post #137
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…

All modern Boeings (>= B777) are FBW (fly by wire) and have flight envelope protection. A 787 will absolutely not go over-speed: it will automatically throttle back.

[deleted]

Re: A330 flight control laws saved Voyager, inquiry finds

#150

Post by hollander »

nathancahill wrote: post #85
closeparen wrote: post #83

Earlier quoted context omitted.

Is it me or has seat-belt-sign discipline gone out the window? Over my December travels, dozens of passengers on all 4 segments I flew openly flaunted the seat-belt sign, getting up to go to the bathroom and standing in the aisle waiting for it in full view of flight attendants, who didn't say anything. I broke down and did so myself, as the seat belt sign was on for the vast majority of the flight and I was getting…

I've noticed that too. I used to do that myself, until I hit some of the worst turbulence of my life flying in to Denver a couple years ago. Whacked my head pretty hard on main cabin ceiling (the plane dropped ~20ft without warning and I didn't). Ever since then I've worn my seat belt for as much of the flight as possible.

During flight, you can set the belt a bit looser. For cases like this it's more important to keep you in your seat, than to keep you there as tight as possible, which is more important in case of a crash.
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