Gatwick bosses learnt that a damaging flood would hit the airport only half an hour before it happened on Christmas Eve, the Sussex airport's chief told MPs.
The flooding was the worst at the airport since 1967, Gatwick chief executive Stewart Wingate told the House of Commons Transport Committee.
He said he was "very sorry" about what happened on Christmas Eve when many flights had to be cancelled and others were badly delayed.
Mr Wingate went on: "A lot more could and should have been done for passengers. Our actions fell short."
He was speaking at a special one-off evidence session called following the major flood-related disruption at Gatwick on Christmas Eve which led to flight cancellations and long delays.
Passengers complained about a lack of information, with some waiting many hours for flights before having to go home after learning that their flight had, ultimately, been axed.
Gatwick has invited all those who flights were cancelled on Christmas Eve to apply for £100 shopping vouchers as a gesture of goodwill.
Gatwick has begun its own investigation into the pre-Christmas problems while the Civil Aviation Authority has said it is looking into the matter.