Air france flight from Brazil to Paris

[Matt308]

Below are the messages tied to coded ATA-JASC codes with time. Note that where the messages codes do not match my ATA-JASC codes, I have only included the major ATA-JASC chapter, but could not find the subchapters. You might have more luck. Also not being completely familiar with the A330 autoflight/autothrottle system acronyms, I have flagged those where I was guesstimating message content.

The ATA-JASC codes/time indicate in rough order:

May 31st
2245
Water Waste/Wast Disposal System Maintenance Status warning
Water Waste/Wast Disposal System (message content unknown to me) references Lavatory and likely Lavatory location (X2?) failure


June 1st
0210
Pitot Probe failure
Air Temp Indicator/Sensor failure
Auto Flight System warning
Auto Flight/Autopilot System Off warning
Auto Flight (ATA 27-93?) Alternate Control Law warning
Auto Flight (ATA 22-83?) Flags on both Capt/FO Primary Flight Display warning (autopilot disconnect flags) warning
Auto Flight/Auto Throttle System Off warning
Navigation/Doppler System (ATA 34-43?) Navigation TCAS Fault warning
Auto Flight (ATA 22-83?) Flags on both Capt/FO Primary Flight Display warning (autothrottle disconnect flags) warning
Flight Controls (ATA 27-23?) Flight Control Rudder Travel Limiter Fault warning

0211
Navigation/Outside Air Temp Indicator-Sensor Flag on Capt/FO Primary Flight Display warning
Two failure messages ATA 34-12 Navigation/Outside Air Temp Indicator-Sensor (Message content unknown to me. IR1, IR2, IR3 Inertial Reference Unit failures perhaps?)

0212
Navigation/Flight Environment Data - Navigation ADR (Air-Data Intertial Reference Unit?) Disagree warning

0213
Two warning messages for Flight Controls (ATA 27-90?) Flight Control Primary/Secondary Fault
Autoflight (ATA 22-83?) message content unknown to me. AFS=Autoflight System?

0214
Navigation/Flight Environment Data Maintenance warning
Air Conditioning/Cabin Pressure Controller warning

[syscom3]

Originally Posted by DerAdlerIstGelandet

Come on Joe, that is not possible! Computers and automated cockpits don't make mistakes! Ain't that right Sys?

You score a point

[Matt308]

Also note that the ACARS messages summary are public domain. This is NOT considered any of the sensative accident information deemed not suitable for public consumption at this time.

[The Basket]

If the pitot tubes were all frozen then the pilot wouldn't know his altitude or his speed.

He would have no visual references either.

If the aircraft had somehow entered into a steep dive but still not with the idea it broke up in midair. But the pilot was flying blind with all sorts of whistles and buzzers blaring.

There was a case of a South American airliner which had all its pitots taped up and the pilots ended up flying it into the ground at night. They had no idea what was going on. If you're told to trust your instruments and they go all crazy in zero visibilty then you're donald ducked.

[Matt308]

And the ACARS messages would support that hypothesis.

[Burmese Bandit]

Which brings us to the question: are not modern aircraft, and aircraft built to the Airbus design philosophy in particular, specifically built so that this sort of thing can not happen?

[Matt308]

CAN NOT are strong words, BB. Modern air transport airplanes are built with fault tolerant systems. These systems have triple and quadruple redundancy built into them, as well as dissimilar designs to minimize common mode failures. But a system which 'CAN NOT' fail has never been been designed...Only the likelihood of that failure occurring minimized to an 'acceptable' level. And that equates to $$$. The dirty secret in the accident/incident investigative world is that deaths=$$$ when evaluating cost analyses for aircraft designs. And some deaths are actually 'acceptable'. Folks may not wish to believe this, but it is true. I know first hand.

[Vassili Zaitzev]

Basket, you're talking about Aeroperu flight 603. Their static ports were covered with duct tape during cleaning, and were never taken off. The CVR recordings are on youtube. They had multiple alarms going off with no visibility. The pilots had no idea what their altitude was, until they hit the water.

So I guess in essence, these two flights are similar. Both planes had problems with their instruments, and the pilots had no visibility.

[syscom3]

I believe the flight panel does have a traditional artificial horizon and altimeter for the pilot to use in case the digital display blanks out.

It seems quite likely that the plane did stall due to the pitot tubes freezing. But a stall in itself shouldn't cause the aircraft to breakup.

[gumbyk]

Originally Posted by syscom3

It seems quite likely that the plane did stall due to the pitot tubes freezing. But a stall in itself shouldn't cause the aircraft to breakup.

Would a stall/spin situation lead to a break-up? I can't imagine that something of that size would last too long with the forces generated in a spin.

[Vassili Zaitzev]

if the stall was uncontrollable, no doubt the plane accerlated beyond it's safety limits. That may be why the plane broke up in midair.

[Matt308]

Originally Posted by muller

I caught the tail end of an interview with an Aer Lingus pilot on the news this eveneing, he was talking about the speed sensors on the airbus failing and the flight control system not knowing what speed the aircraft was going and hitting 'coffin corner'. Just googled it.


Wiki- Coffin Corner.

"The coffin corner or Q-Corner is the altitude at or near which an aircraft's stall speed is equal to the critical Mach number, at a given gross weight and G loading. At this altitude the aircraft becomes nearly impossible to keep in stable flight. Since the stall speed is the minimum speed required to maintain level flight, any reduction in speed will cause the airplane to stall and lose altitude. Since the critical Mach number is maximum speed at which air can travel over the wings without losing lift due to flow separation and shock waves, any increase in speed will cause the airplane to lose lift, or to pitch heavily nose-down, and lose altitude. The "corner" refers to the triangular shape at the top of a flight envelope chart where the stall speed and critical Mach number lines come together."

Consequences.

"When an aircraft slows to below its stall speed (or more properly, when the wing exceeds its critical angle of attack), the airflow over the top of the wing separates from the wing surface, and lift decreases dramatically (the wing "stalls"). Because the lift reduces while the aircraft's weight does not, the aircraft loses altitude. When the aircraft exceeds its critical Mach number, then drag increases or Mach tuck occurs, which can cause the aircraft to upset, lose control, and lose altitude. In either case, as the airplane falls, it could gain speed and then structural failure could occur.

As an aircraft approaches its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller. Small changes could put one wing or the other above or below the limits. For instance, a turn causes the inner wing to have a lower airspeed, and the outer wing, a higher airspeed. The aircraft could exceed both limits at once. Or, turbulence could cause the airspeed to change suddenly, to beyond the limits."

Nobody read (or perhaps understood) Muller's post.

[vikingBerserker]

It's really odd that the pilot never radioed anything.

[Vassili Zaitzev]

Matt, I read it, but really didn't understand it. Sorry, got a little complicated, I'll take another gander.

[gumbyk]

Vassili, I'll try to paraphrase from what I understand. Matt, please correct anything which isn't correct.

As an aircraft flies higher, the stall speed increases, and the critical mach number decreases. Eventually you reach a point where the two are almost the same figure. Any faster and you will get mach tuck (nose pitch down, and more over-speed), any slower and you will stall the aircraft (nose pitch up in a swept wing aircraft).

There are other things which affect the stall and cricical mach speeds, such as temperature, so I would guess, theoretically at least, severe up/down drafts could have placed them in 'coffin corner'.