Airbus Laws
With regard to the A330.
NORMAL LAW
Consists of three modes - in order of occurrence GND/FLT/FLARE and GND again at landing. Transition between each is conditional on factors like pitch attitude, RA, time and whether the aircraft is on the ground or in flight. The position of the landing gear has no effect on normal law control and complete flight envelope protection is provided in FLT mode.
ALTERNATE LAW
There are numerous combinations of failures which will result in a reconfiguration into ALT LAW. There are two types both of which are characterised by pitch control which is very similar to normal law pitch control. In both types of ALT LAW the protections are almost totally lost except for load factor protection. Availability of high and low speed stabilities is conditional as well. Audio stall warning is activated in both types at a safe margin from actual stall. Gear extension may require some forethought as in some cases (e.g. EMER ELEC CONFIG) the autotrim is lost.
DIRECT LAW
This condition is arrived at as a result of failures like triple IR/PRIM. Pitch and roll are in direct law - direct sidestick to surface relationship. There is no autotrim and ALL protections are lost. Again gear extension may require some forward planning.
There is one hybrid type failure which can cause confusion and that is the dual RA fault. RA is one of the primary inputs for normal law control of transition from flight mode to flare mode. Instead of RA information the flight control system uses inputs from the LGCIU to determine mode switching. So when the gear is down in this case a switch to flare mode occurs and autotrim is lost. EGPWS is inoperative and the low energy warning is lost as well.
Long-winded I know but hope it helps.