Air France pilots battled for 15 minutes to save doomed flight AF 447

Telegraph ^

[traumer]

Air France pilots battled for up to 15 minutes to save the doomed flight that went missing over the Atlantic this week, electronic messages emitted by the aircraft have revealed.

Details have emerged of the moments leading up to the disappearance of flight AF 447 with 228 people on-board, with error messages reportedly suggesting the plane was flying too slowly and that two key computers malfunctioned.

Flight data messages provided by an Air France source show the precise chronology of events of flight AF 447 before it plummeted into the sea 400 miles off Brazil on Monday.

These indicate that the pilot reported hitting tropical turbulence at 3am (BST), shortly before reaching Senegalese airspace. It said the plane had passed through tall, dense cumulonimbus thunderclouds.

At this stage, according to a source close to the investigation cited by Le Monde, the Airbus A330-200's speed was "erroneous" - either too fast or too slow. Each plane has an optimal speed when passing through difficult weather conditions, which for unknown reasons, had not been reached by flight AF 447.

Airbus is expected to issue recommendations today to all operators of the A330 model to maintain appropriate thrust levels to steady the plane's flight path in storms.

At 3.10am, the messages show the pilot was presented with a series of major failures over a four-minute period before catastrophe struck, according to automatic data signals cited by the Sao Paulo newspaper, le Jornal da Tarde.

At this time, the automatic pilot was disconnected – either by the pilot or by the plane's inbuilt security system, which flips to manual after detecting a serious error.

[justlurking]

Does the 330 have ‘stick shaker’, or, joystick shaker, I guess? If so, does the autopilot automatically disengage when it activates?

I don't know for sure, but the non-authoritative information I've found says that the 330 with the side-stick controller does NOT have a stick shaker.

The fly-by-wire system does have a de-facto stick "pusher" -- or more accurately, the flight control system will avoid or recover the plane from a stall as long as it is still working and you aren't close enough to the ground that it thinks you are landing.

I don't know what the autopilot does under those circumstances, once it recovers from the stall.

[ArmstedFragg]

I located a chart of exactly what’s enabled and what isn’t for each operational state somewhere online. I’m trying to remember the search now...

Oh, here it is:

http://www.airbusdriver.net/airbus_fltlaws.htm

There’s reference to the pseudo-pusher there, too.

The details are so cobbled up at the moment, I’m at a loss to explain why there are so many “informed judgments” about what took place. Just today, I’ve heard the piece of data about speed described as being both over speed and under speed. And, of course, we now have word that the debris found wasn’t from the aircraft. I don’t think we’ll really know anything until the FDR is recovered.

[Hulka]

Please re-read Post 120.

Absent totality of facts, we cannot know for 100% certainty what happened. We can discuss probable causes and most likely causes, but at this stage of the mishap investigation it is premature to allege as fact a specific cause. We have good information regarding a probable sequence of events defining the inflight breakup, but we have no certainty of the initiating cause/event of the breakup. The preponderance of subjective interpretation favors inflight breakup due to extreme weather conditions, but we don't know if this is the cause.

I can only believe that given your swift certain judgment you are not a) trained in aviation mishap investigation, and b) never participated in aviation mishaps investigations.

That's okay, everyone has an opinion and you have yours.

[Lazamataz]

I’m sorry, Dave. I can’t fly that.

[NittanyLion]

According to a poster on PPRuNe.net ,"The Air Comet flight was 7° north and 49° west while the AF 447 was something like 30° west [mine - and on the Equator]."

Source

[AirPlain]

The HF radio used by transport aircraft is SSB (single side band) and is very effective over long distances. It doesn’t matter about the local interference from the storm because where the signal will be received it is probably electrically “quiet” and not influenced by the interference at the origin end. Most likely, the data was transmitted over a satellite data link which would support high speed and be very reliable.
The events, as outlined, show a very troubled aircraft coming apart in flight for whatever reason. A tragedy by any measure.