Trainer Kenneth Peters was bitten and held underwater several times by a 700-pound killer whale during a show at Shamu Stadium on 29 November.
He escaped with a broken foot and was in hospital for three days.
An official report says Mr Peters survived the attack because he stayed calm.
But the report goes on to say that swimming with captive orcas "is inherently dangerous and if someone hasn't been killed already it is only a matter of time before it does happen".
A SeaWorld San Diego official disagreed with some of the report's findings and said that its conclusions reflected a lack of understanding of whale behaviour.
He denied that the death of a trainer was inevitable.