The relationship between the Pilot Flying’s (PF’s) input on the sidestick, and the aircraft’s response, is referred to as a Flight Control Law. The Flight Control Law in operation determines the handling characteristics of the aircraft.
There are three main sets of Flight Control Laws, one of which will be active at any given time according to the status of:
- Flight Control Computers
- Flight Control System Peripherals
- Hydraulic systems
The three main sets of Flight Control Laws are:
- Normal Law
- Alternate Law
- Direct Law
Alternate Law and Direct Law are reconfiguration levels that provide redundancy in the event of certain failures.
In the event of a complete loss of electrical power, the loss of all five fly-by-wire computers, the loss of both elevators or the total loss of ailerons and spoilers, Mechanical Backup is available to stabilize the aircraft while the crew reconfigures the aircraft systems.
Under certain circumstances (e.g. AAR Operations) Normal and Alternate Laws can be supplemented by two Flight Control Law subsets:
- Tanker Law
- Receiver Law
The relationship between the ARO’s input on the Boom Flight controls and the Advanced Refuelling Boom System response is also governed by control laws.