[Moose4]

Posts over on airliners.net seemed to indicate that the three-or-four minute sequence of automated ACARS messages indicated some sort of electrical faults, followed by an autopilot disconnect, then ADIRU (air data inertial reference unit, I think) and standby instrument faults, then faults on the primary and one secondary flight computer, and finally an excessive cabin vertical speed warning that might indicate a depressurization. So whatever happened to AF447 wasn’t one massive failure like a Pan Am 103 or a TWA 800. Things failed over a span of at least four minutes, apparently in a cascade of increasing severity.

The thing that concerns me is that even if they do find the recorders, if there were electrical problems, it’s possible that they might not have all the data on them. When the Swissair MD-11 crashed off Nova Scotia in 1998, both recorders stopped fully six minutes before impact because they lost electrical power.

}:-)4

[r9etb]

Posts over on airliners.net seemed to indicate that the three-or-four minute sequence of automated ACARS messages indicated some sort of electrical faults, followed by an autopilot disconnect, then ADIRU (air data inertial reference unit, I think) and standby instrument faults, then faults on the primary and one secondary flight computer, and finally an excessive cabin vertical speed warning that might indicate a depressurization. So whatever happened to AF447 wasn’t one massive failure like a Pan Am 103 or a TWA 800. Things failed over a span of at least four minutes, apparently in a cascade of increasing severity.

Not an expert here, but the progression (reports of turbulence, a cascade of failures, etc.) sounds to me like there may have been some sort of progressive structural problem, perhaps brought on by the initial turbulence.

[TalonDJ]

Posts over on airliners.net seemed to indicate that the three-or-four minute sequence of automated ACARS messages indicated some sort of electrical faults, followed by an autopilot disconnect, then ADIRU (air data inertial reference unit, I think) and standby instrument faults, then faults on the primary and one secondary flight computer, and finally an excessive cabin vertical speed warning that might indicate a depressurization. So whatever happened to AF447 wasn’t one massive failure like a Pan Am 103 or a TWA 800. Things failed over a span of at least four minutes, apparently in a cascade of increasing severity.

A sequence like that could have been an in air break up. Remember those indications are not indications of root problems but of the symptoms. Many things can cause autopilot disconnect. Same with the ADIRU. Both of those would indicate failures if the aircraft went had severe upset.

here is an example.
Planes rudder breaks off (there is not 'tail off indicate)
Extreme yaw shears an engine off.
electrical system loses the generator that was on that engine and registers an error
-- electrical error is sent out
The extreme yaw causes the autopilot to disconnect (it will do that)
-- autopilot error sent out
A wing comes off.
The standby indicator has lost contact with several systems it needs to function and
--it reports an error
The computers have lost contact with many systems and sensors. They go into a faulted state.
--they report errors
Plane is falling and tumbling. Cabin breaks open.
Cabin pressure drops suddenly. This is referred to as cabin Altitude. The result is that the cabin altitude reading just went 'up' by thousands of feet.
-- cabin altitude error is reported.


I am not saying this is the right sequence. But this is an example of how one thing (turbulence taking the rudder off) can register as a series of failures as things go down the tubes.

I am not familiar with this particular plane or how it's failures are reported but I have spent an number of years as an avionics engineer.