[Yo-Yo]

to request the US Navy to train its test pilots in catapult assisted take-off and barrier arrested recovery (Catobar).

CATOBAR = Catapult Assisted Take Off But Arrested Recovery.

Barrier recovery is what they use if the aircraft can't lower their hook.

[A.A. Cunningham]

Barrier recovery is what they use if the aircraft can't lower their hook.

There are many other reasons to raise the barrier if the hook won't come down. As the picture shows, that Intruder has snagged the #2 wire.