@Marty-R It depends on the situation:
Scenario 1:
A carrier with planes (same power) is the attacker: In this case the carrier and the planes move independently, so the planes are already in the air while the carrier moves. So the carrier does not actually carry cargo when it is hit. However the planes can’t land on a damaged carrier and need to spend their remaining movement points to (hopefully) land.
Scenario 2:
A carrier with planes (friendly power=“guest aircraft”) is part of the attacking force: In this case it is only the carrier that moves, as the friendly planes are cargo. In case the carrier is hit only once the planes are stuck on the carrier until it gets repaired, as they can’t launch from a damaged carrier when it is their turn.
Scenario 3:
A carrier with planes (either same power or friendly power) is the defender: When the carrier is attacked the planes are considered to be defending in the air. So the carrier does not actually carry cargo when it is hit. So when the carrier is hit, the planes need to search for an alternative landing place within the range of 1 space. (This is @koala 's above scenario.)
By the rules planes are only considered being cargo when they are on a friendly power’s attacking carrier (“guest aircraft” - scenario 2). And cargo simply sinks with the carrier, there is no extra move.
