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Old 8th Jul 2011, 22:27
  #1048 (permalink)  
mm43
 
Join Date: Jun 2009
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ALT-1, ALT-2 or ABNORMAL ATTITUDE LAW

I thought the June 01, 2011 David Kaminski-Morrow article in Flight Global had been accepted as a genuine BEA leak to counter forum posts etc. that had deduced that the aircraft was in Abnormal Attitude Law.

Furthermore, there are still references being made to ALT-1, whereas the general consensus is that ALT-2 is the law applicable.

From post #1567 Thread No.3 - the FCOM provides the following statement on ABNORMAL ATTITUDE LAW -

An abnormal attitude law in pitch and roll is provided, if the aircraft is in flight and in any of these conditions:
- Pitch attitude > 50° node up or 30° nose down
- Bank angle > 125°
- Angle of attack > 30° or < - 10°
- Speed > 440 knots or < 60 knots
- Mach > 0.96 or < 0.1
The law in pitch is the alternate law without protection (except load factor protection) and without auto trim. In roll, it is a full authority direct law with yaw alternate.
After recovery, the flight laws are:
In pitch : Alternate law.
In roll : Direct law with yaw alternate.
First reading of the above leads one to believe that each of the conditions is mutually exclusive, but if the Flight Global report is to be believed, that is not the case. The new interpretation is that the conditions are mutually exclusive PROVIDED all the ADRs haven't been rejected, but should all the ADRs be rejected, then an inertial upset involving either of the first two items will revert the aircraft to ABNORMAL ATTITUDE LAW.

If this was the case, the MAN PITCH TRIM ONLY was not displayed, as auto trim was still available.

Don't take it all as "gospel", as that is not what the FCOM currently says.

See post #1571 by A33Zab for details.
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