Paging Fly320s - French A330 Crash of 2009

[Ben]

The French have apparently just released the full investigation of the crash. As in most crashes, the indications are pilot error. From the article:

In one fatal decision, the report says, one of the co-pilots in the cockpit at the time nosed the Airbus A330 upward during a stall -- instead of downward, as he should have -- because of false data from sensors about the plane's position.

Read more: http://www.foxnews.com/world/2012/07/05/final-report-expected-on-france-brazil-plane-crash/?test=latestnews#ixzz1zl5HlTz2

The quote has me curious - are there no analog / mechanical attitude indicators in commercial airliners as a "backup" for faulty electronics? I'm assuming the fault with the readout was electronic? With no mechanical means of confirmation, it's harder to find all fault with the pilots, since if I recall, they were in disorienting IFR conditions.

[Boomhauer]

are there no analog / mechanical attitude indicators

They are trending towards an electronic backup that is supposed to be independent with it's own battery power supply.

No, it's not a trend that I agree with. I like a good old fashioned mechanical gyro backup. They make decent ones that have electrically spun gyros with their own batteries and all that.

[Fly320s]

I haven't read the final report, but I did read a preliminary report.

IIRC, the faulty instrument was the airspeed indicator(s), not the artificial horizon. The pilot pitched the nose up due to an excessive airspeed indication.

All commercial airplanes have backup instruments. Some are independant systems, some are redundant systems with independant power supplies. If the A330 is the same as the A320, then the backup airspeed indicator is independant, but the backup artificial horizon (attitude indicator) uses the same data from the inertial reference system, but it does have independant power with battery back up.

I'll read the final report and get back to you tonight.

[Doggy Daddy]

Not an aviation expert, but I seem to recall from some earlier reading that they were flying into a storm rather than go around and their pitot tubes froze up causing the lack of proper airspeed info.  I seem to recall the positioning of the joysticks (out of sight of the other pilot) was a contributing factor, along with the fact that the senior pilot had gone to take a nap.

Is that about right?

DD

[Fly320s]

Not an aviation expert, but I seem to recall from some earlier reading that they were flying into a storm rather than go around and their pitot tubes froze up causing the lack of proper airspeed info.  I seem to recall the positioning of the joysticks (out of sight of the other pilot) was a contributing factor, along with the fact that the senior pilot had gone to take a nap.

Is that about right?

DD

Yep.

Anyone have a link to the final report?

[tokugawa]

I still don't understand how someone could hold the stick full back, when he had an attitude indicator, and an altimeter, and the stall warning was going off.   And blow through 30,000 feet of air that way. 
 It sounds like he just panicked.
  I would be interested to know if the altimeter was a digital numeric, or analog with a needle- I think for quick reading at a glance, analog is better, because you do not need to do a mental translation of numbers to effects.

[Fly320s]

Altimeter is a digital vertical tape displayed on the left side of the primary flight display (crt screen).

As for ignoring all of the other indications and warnings, that pilot probably had target fixation. The airspeed was the first (maybe only) system to fail.

[Hawkmoon]

Altimeter is a digital vertical tape displayed on the left side of the primary flight display (crt screen).

As for ignoring all of the other indications and warnings, that pilot probably had target fixation. The airspeed was the first (maybe only) system to fail.

Could the altimeter have been similarly fubared?

[Jamisjockey]

Target fixation seems to be immediately followed by panic when you realize you were target fixated.
At least in my experience....

[Stand_watie]

I read the popular mechanics (?) synopsis a while back. I was amazed at how familiar the failures sounded to someone who has no  specialized aviation knowledge.

edit; http://www.popularmechanics.com/technology/aviation/crashes/what-really-happened-aboard-air-france-447-6611877

[Hawkmoon]

I remember reading an article a short time after the black box had been recovered. The crux of the issue seems to have been the Airbus fly by wire controls:

Unlike the control yokes of a Boeing jetliner, the side sticks on an Airbus are "asynchronous"—that is, they move independently. "If the person in the right seat is pulling back on the joystick, the person in the left seat doesn't feel it," says Dr. David Esser, a professor of aeronautical science at Embry-Riddle Aeronautical University. "Their stick doesn't move just because the other one does, unlike the old-fashioned mechanical systems like you find in small planes, where if you turn one, the [other] one turns the same way." Robert has no idea that, despite their conversation about descending, Bonin has continued to pull back on the side stick.

[Fly320s]

Could the altimeter have been similarly fubared?

Possible, but there was no inication of that in the preliminary report.

I remember reading an article a short time after the black box had been recovered. The crux of the issue seems to have been the Airbus fly by wire controls:

True, one pilot can't really tell what the other pilot is doing with the sidestick, but there is an easy way for one pilot to override the control input the other pilot has made. On the sidestick is a red button that is used to disconnect the autopilot and if held down, if gives that sidestick priority.

[dogmush]

True, one pilot can't really tell what the other pilot is doing with the sidestick, but there is an easy way for one pilot to override the control input the other pilot has made. On the sidestick is a red button that is used to disconnect the autopilot and if held down, if gives that sidestick priority.

What happens if both pilots hold down the litlle red button?

[roo_ster]

What happens if both pilots hold down the litlle red button?

[AJ Dual]

Watched the NOVA special about this. What I had not known was that at a given altitude, air pressure, and the lift dynamics of the nominal airliner's wing dictate a cruise speed where you literally have only 5kts or whatever leeway + or - over the ideal speed, or you'll go into a stall.

A few knots too slow, and you're not generating enough lift for that altitude/air pressure. Too fast, and pre-Mach 1/sonic shockwaves begin to form and you get airflow separation from the wing. (Which I guess was the point of delta or swing-wings? So some part of the wing still always "bites" as these shockwaves form...)

I had no idea the "sweet spot" in airspeed for a given altitude/air-pressure was so narrow, or you will stall or suffer loss of positive control. And I can forgive the pilot(s) for getting target fixation on (what he thought was) his airpseed because the pitot tube/airspeed indicator froze shut.

If I remember what the experts in the NOVA show were saying correctly, pilots are taught a standardized maneuver to survive this very situation with massive instrument failure, where a predetermined throttle setting,  and specific aircraft pitch pretty much guarantees you a certain airspeed, no matter what the instruments say. However, this model of Airbus' fly-by-wire system does NOT move the throttles to give extra visual feedback to the crew. So they pitched the aircraft to try and force the airspeed they wanted, but didn't manually move the throttles. Plane stalled then spun...

[Fly320s]

What happens if both pilots hold down the litlle red button?

Last one wins.  In an absolute tie? Probably defaults to the last active sidestick.

[Hawkmoon]

Last one wins.  In an absolute tie? Probably defaults to the last active sidestick.

This new article implies that they (the circuits) sort of average the inputs.

[Fly320s]

This new article implies that they (the circuits) sort of average the inputs.

That is true when they are moved simultaneously and the takeover button is not pushed.

[Fly320s]

Someone asked about the altimeter... looks like this.  Left screen, altimeter is the strip on the right. Showing us climbing through 19,800 on the way to 34,000.

[Fly320s]

The location of the secret APS bunker.

[Hawkmoon]

Someone asked about the altimeter... looks like this.  Left screen, altimeter is the strip on the right. Showing us climbing through 19,800 on the way to 34,000.

Looks like a video game.

Whatever happened to dials?



Now THERE's an altimeter.

[Tallpine]

Left side (300+) is knots 

.657 Mach ? 

[Fly320s]

Left side (300+) is knots 

.657 Mach ? 

Yep, indicated airspeed of 303kts. That is .657 Mach at that altitude. Around 23,000 we transition to using Mach speed instead of indicated airspeed.  We normally cruise at .78 mach.

[Fly320s]

Looks like a video game.

Whatever happened to dials?

Now THERE's an altimeter.

Dials is heavy. Electronics is light and more functional.

[tokugawa]

Still, ya gotta wonder if an analog altimeter unwinding widdershinns like an insane clock running backwards might have woken someone up.....