Considering the scenario of an upset caused either by a faulty ADIRU or bad weather the crew could have easily found themshelves operating under the ABNORMAL LAW.
ABNORMAL ATTITUDE FLIGHT LAW
A completely different law emerges automatically when the aircraft is in an extreme upset as follows:
* pitch attitude > 50 deg nose up or > 30 deg nose down
* bank angle > 125 deg
* AOA > 30 deg or >-10 deg
* speed > 440 kts or < 60 kts
* mach > M0.96 or < M0.1
The abnormal attitude law is:
- PITCH ALTERNATE with no protection except LOAD FACTOR protection. No automatic pitch trim.
- ROLL DIRECT with full authority
- YAW ALTERNATE
After recovery the flight law reverts to:
- PITCH ALTERNATE law
- ROLL DIRECT law
- YAW ALTERNATE
The aircraft returns to a degraded mode (not normal law as usual) because there is a certain level of suspicion about its ability to control the aircraft (that is how could it have got to the extreme flight state in the first place? The protections should have intervened well before the pitch, bank, AOA, speed and mach limits above).
I wonder what indications the crew have to realise they have entered this abnormal law? It could be very difficult in a bussy and turbulent enviroment to give an adecuate response to this type of scenario.
What are your toughts??