Budget air carrier Ryanair ( NASDAQ: RYAAY) announced Saturday it would be canceling 40 to 50 flights per day for the next six weeks after scheduling mistakes. They didn't factor in crew vacations.

“We f---ed up here, and we have to fix it. We should have seen it coming. This will have a reputational impact,” said CEO Michael O’Leary on a conference call.

The budget airliner could stand to lose $30 million and the cancellations could affect up to 400,000 passengers, according to Bloomberg Monday.

“We have messed up in the planning of pilot holidays and we're working hard to fix that,” said Chief Marketing Officer Kenny Jacobs to the BBC Sunday.

The Ireland-based company faces a backlog of mandatory crew vacations as outlined by Irish authorities.

“We were trying to give too many pilots blocks of four weeks leave,” said O’Leary. “We have mismanaged that process.”

The cancellations will affect about two percent of the carrier’s daily flights. In order to help e soften the blow of the situation, Ryanair plans a fare sale, to offer bonuses to pilots willing to sacrifice vacation days and to hire more crews.

Ryanair has listed all flights it has canceled through Sept. 20 on its website. The carrier is offering fee-free flight changes and refunds.

European Union rules have much greater protections for flight passengers than in the U.S.

“It is the potential for long-term damage that concerns us. The poor [public relations] could deter future bookings and may well put off more time-sensitive higher yielding demand, like business trips, if the carrier is seen as unreliable and less punctual,” said a note to clients of RBC Capital Markets Monday.

O’Leary apologized on behalf of Ryanair on the call.

“My apologies to our investors but also primarily to our customers for any uncertainty or any inconvenience we’ve caused you over the weekend,” O’Leary said. “It wasn’t done lightly, it wasn’t done out of some dismissive or ‘don’t care’ attitude.”