Air France A330-200 missing

[theballetbrusque]

Alternate Law

ALTERNATE LAW If Multiple Failures of Redundant Systems occur, the flight controls revert to Alternate Law.
The ECAM displays the message: ALTN LAW: PROT LOST Ground
Mode The ground mode is identical to Normal Law. Flight
Mode

• In pitch alternate law the flight mode is a load factor demand law similar to the Normal Law flight mode, with reduced protections.
• Pitch alternate law degrades to pitch direct law when the landing gear is extended to provide feel for flare and landing, since there is no flare mode when pitch normal law is lost.
• Automatic pitch trim and yaw damping (with limited authority) is available.
• Turn coordination is lost.
• When pitch law degrades from normal law, roll degrades to Direct Law - roll rate depends on airspeed.

Protections

• All protections except for load factor maneuvering protection are lost.
• The load factor limitation is similar to to that under Normal Law.
• Amber XX's replace the green = attitude limits on the PFD.
• A low speed stability function replaces the normal angle-of-attack protection
  • System introduces a progressive nose down command which attempts to prevent the speed from decaying further.
  • This command CAN be overridden by sidestick input.
  • The airplane CAN be stalled in Alternate Law.
  • An audio stall warning consisting of "crickets" and a "STALL" aural message is activated.
  • The Alpha Floor function is inoperative.
• The PFD airspeed scale is modified:
  • VLS remains displayed
  • VALPHA PROT and VALPHA MAX are removed
  • They are replaced by a red and black barber pole, the top indicating the stall warning speed VSW
• A nose up command is introduced any time the airplane exceeds VMO/MMO to keep the speed from increasing further, which CAN be overridden by the sidestick.
• Bank angle protection is lost.
• Certain failures cause the system to revert to Alternate Law without speed stability.
• Yaw damping is lost if the fault is a triple ADR failure.

ABNORMAL ALTERNATE LAW Abnormal Alternate Law is activated if the airplane enters an unusual attitude, allowing recovery from the unusual attitude.

• Pitch law becomes Alternate (without autotrim or protection other than Load Factor protection).
• Roll law becomes Direct law with mechanical yaw control.
• After recovery from the unusual attitude, the following laws are active for the remainder of the flight:
  • Pitch: Alternate law without protections and with autotrim.
  • Roll: Direct law
  • Yaw: Alternate law
• There is no reversion to Direct law when the landing gear is extended.