AF447 - What really happened, Popular Mechanics Article

[HawkDsl 50]

I'm not yet a pilot, but both my father and brother are. In all my travels with them aloft, stalling, and what to do, was (and IS) always 1 and 1a to them. A similar crash with an American Eagle turbo prop pond jumper had the same thing happen... yanking the stick back to bending point.I'm very sad for all those people. They had control for a moment... then fear and panic took over. A state I hope no one will have to face no matter where you are.. ground or air.

[Guest jahman]

The article adds an important element not considered previously: An explanation for Bonin's inexplicable climb.Sudden icing deposited on the fuselage from the nose back to the cockpit, thus causing a sudden increase in slipstream loudness. This increase in sound level would be interpreted almost instinctively by many a pilot as an increase in IAS, especially in the midst of a dark and stormy night with no reliable IAS indication.

(from article) Then the sound of slipstream suddenly becomes louder. This, presumably, is due to the accumulation of ice crystals on the exterior of the fuselage. Bonin announces that he is going to reduce the speed of the aircraft

Note that sound is the most powerful of the senses in terms of generating fight or flight response and is the only sense not disconnected during sleep.Thus Bonin was frightened by the sudden increase in slipstream sound and elected to climb to avoid exceeding Mmo and entering an unrecoverable mach tuck,From personal RW experience flying a glider, I could get pretty good at estimating IAS from the cockpit sound level. If Bonin was also a glider pilot in his free time, this relationship netween cockpit sound level and IAS could have been reinforced in him.Cheers,- jahman.

[FLEX1978 373]

Same thing for the 10000fpm descent, the wind sound rushing past the cockpit would be loud, this must have been extremely confusing since if the aircraft is stalled at 60kts you would expect to hear almost no wind rushing past the cockpit.This was tested in the level-d sims, they found it was not programmed correctly and wind sound was not connected to vertical speed. You can test this in FS, put any aircraft into a stall, hold the nose until the IAS is extremely low and then let the vs drop, you will hear no increase in the sound of air rushing past the cockpit unless you have forward speed.I too was convinced they thought they were near overspeed however a simple fact blows that out of the water - they selected TOGA Thrust and left it there till impact. Who would do that when in fear of overspeed?Regards

[Raindance 25]

Could TOGA thrust ever have recovered the situation given enough time/altitude (which they obviously didn't have) with the stick pulled back as it was?

[MarkW 1,491]

Thanks for the FCOM info on the mode warnings.

[FLEX1978 373]

Could TOGA thrust ever have recovered the situation given enough time/altitude (which they obviously didn't have) with the stick pulled back as it was?

No, they needed to get the nose down and reduce the angle of attack, unless in a fighter jet or the space shuttle thrust alone is not going to do much, they needed air flowing over the wings.Regards

[Guest jahman]

Same thing for the 10000fpm descent, the wind sound rushing past the cockpit would be loud, this must have been extremely confusing since if the aircraft is stalled at 60kts you would expect to hear almost no wind rushing past the cockpit....

Good point! I wonder if the investigators measured cockpit background noise from the CVR...Cheers,- jahman.

[mgh 89]

It's always worth reading the report::

At 2 h 12 min 04, the PF said that he thought that they were in an overspeed situation, perhaps because a strong aerodynamic noise dominated in the cockpit. Neither of the two analysed this hypothesis whereas it was inconsistent with the nose-up pitch attitude and the high vertical speed in descent.

BEA's Interim Report #3 Page 76

[Guest jahman]

It's always worth reading the report::BEA's Interim Report #3 Page 76

I was referring more to a background noise dB(SPL) vs. time plot. The fact that noise was increasing as ice was accruing, thus providing a cue of increasing IAS, while the PF was increasing pitch at constant thrust would have been quite disorienting (especially with the IAS indicator inop).Cheers,- jahman.

[ZachLW 37]

The one thing that pains me the most: If the Captain had stepped in just a moment sooner, or the left seat had realized the situation a mere minute or less earlier, there would be no investigation. That irks me more than anything.

[Guest jahman]

The one thing that pains me the most: If the Captain had stepped in just a moment sooner, or the left seat had realized the situation a mere minute or less earlier, there would be no investigation. That irks me more than anything.

Agreed. Iy does seem like the cpatain was always behind events and could never catch-up. Personally I think it should be company policy to have the captain in the cockpit well before traversing the ITCZ with storms appearing on the scope (it takes 15 minutes to get your wits fully about you after waking-up).Cheers,- jahman.

[FLEX1978 373]

Not sure if anyone has seen this before - Below is a similar incident handled correctlyOn May 21, 2009, at 2147 eastern daylight time (EDT), an Airbus A330-233, Brazilian registration PT-MVB, manufacturer serial number 238, operated by TAM Airlines as flight 8091 from Miami International Airport, Florida, to Sao Paulo Guarulhos International Airport, Sao Paulo, Brazil, experienced a loss of primary speed and altitude information while in cruise flight at FL370 over international waters, south of Haiti. The flight crew noted an abrupt drop in outside air temperature and observed St. Elmo’s Fire, followed by the loss of the Air Data Reference System, disconnections of autopilot and autothrust, and loss of primary airspeed and altitude. The flight crew continued using backup instruments, and after a short time, primary data was restored. The airplane remained in alternate flight law and displayed a rudder travel limit flag. The crew determined they could not restore normal law and continued the flight under the appropriate procedures. The flight landed at Sao Paulo with no further incident and there were no injuries or damage. The Brazilian Centro de Investigação e Prevenção de Acidentes Aeronáuticos (CENIPA), delegated the incident investigation into this event to the NTSB.A review of recorded flight data indicated that while level at FL370, indicating mach 0.8 (260 knots), and in moderately turbulent conditions with an outside (static) air temperature of -45º C the No.1 ADR airspeed dropped rapidly from about 260 knots to approximately 60 knots for a few seconds, then rose to 100 knots. At the same time, the recorded pressure altitude dropped by about 300 feet. About one minute later, the autothrust and autopilot disengaged, consistent with the pilot report that the co-pilot’s airspeed also began to fluctuate. The Captain took over and began to fly by reference to the standby airspeed and instruments which he reported still appeared normal. Flight law reverted to alternate and the NAV ADR DISAGREE message was displayed.About 6 seconds after the autopilot disengaged, recorded data indicated two brief re-engagements of the autopilot. Concurrent with the re-engagement, a pitch up to about 7 degrees nose up and slight climb was recorded, and the pilot reported a stall warning. Left side stick pitch inputs were recorded about one second after the autopilot disengaged from the second brief engagement, as the airplane climbed to about 38,000 feet. The autopilot remained disengaged during the remainder of the event, and the crew turned about 60 degrees to the left to diverge from the weather area, and the altitude decreased to about 36,500 feet, before reversing and increasing again. About 3 minutes and 30 seconds after the initial airspeed drop, the No.1 ADR returned to 260 knots, and the 300 foot altitude discontinuity ceased, indicating an altitude of about 37,400 feet. Left nose down stick inputs and a decrease in pitch were concurrent with the altitude returning to 37,000 (FL370). Then autopilot and autothrust were then re-engaged and the flight continued to Sao Paulo in alternate law with no further incident, no injuries, and no damage. Post flight maintenance checks on the airspeed system revealed no discrepancies.

[Guest jahman]

Scary stuff, Rob! Thanks for posting.Some questions I have:

1. Did PT-MVB sport the Thales pitots at the time of the incident?
2. Again there's a climb after IAS becomes unreliable.
3. What did the piltos have to say regarding the incident?
4. How did the pilots react to the incident? (CRM aspect)
5. What were the NTSB recommendations?

Cheers,- jahman.

[Great Ozzie 101]

Some questions I have:- jahman.

Probable Cause Report for PT-MVB (DCA09IA055)The final report for DCA09IA055 was wrapped into report DCA09IA064 (below)Probable CauseFull Narrative

[Guest jahman]

Probable Cause Report for PT-MVB (DCA09IA055)The final report for DCA09IA055 was wrapped into report DCA09IA064 (below)Probable CauseFull Narrative

Many thanks for the links, Rob!Cheers,- jahman.