Monday, May 2, 2011

AF447 FDR's Data Module recovered.

The Data Module that apparently was dislodged from the Flight Data Recorder upon impact was located and roboticly recovered. It appears to be intact based upon gross examination but it is likely to be two weeks before it is known if data can be recovered from it. It is likely to be considerably longer, however, before any recovered data is released to the aviation community or the public. Shear forces on the bolts of the data module and the ultrasonic pinger are unknown but separation of the data module from the chassis of the FDR has taken place in prior crashes involving impact with water. The BEA has not released definitive data on the pinger but it is believed that signals were recorded by the French submarine involved in the search but not detected at the time by sonar operators. Later data scrubbing is said to have provided a computerized detection of the pings.

There are so many questions as to why the plane went into an unusual attitude and most particularly as to why there was no recovery despite there being 35,000 feet in order for their to be recovery from a stall. It is possible that a pilot's attempt to re-establish computerized flight control created an additional upset since there is a difference between the plane's attitude and the computer systems processing of the attitude information. Essentially it would be a physical recovery from the stall followed by a systems induced control input that re-established the stalled condition as an unrecoverable deep stall.

There has been much ado about extreme turbulence and the plane's presumed entry into a supercell whose location was masked by a radar detection of a smaller but nearer cell. The trouble with all this turbulent weather assumptions is that other planes transited the area without incident and nothing in the wreckage or bodily injury data indicates that the plane ever encountered severe weather. Galley equipment was not secured and dogged-down as it would be had there been a severe turbulence warning nor was there any indication that all passengers had seat belts securely fastened.

The ACARS system indicates pitot icing problems causing a discrepancy in the speed data the flight computers were receiving. As the computer put the plane into Alternate Law mode and therefore no computer would override pilot input, there would have to have been prompt and proper action by the crew. I can not envision a pilot attempting to re-engage computer controlled flight until the plane itself was known to have recovered from any stalled situation. There was massive loss of data to the pilots and massive cognitive overload as whatever data that was available was unreliable.

As yet, there has been no word concerning the other "black box", the Cockpit Voice Recorder.

No comments: