Jet2 increased revenues 19% to £463 million ($759 million) in the six months ending 30 September, but warns it expects losses in the second half of the year.
The UK leisure airline's passenger numbers were up 13% at 4.1 million. This, it says, was driven by an increase in seats booked with sister tour operator Jet2holidays.
"Our leisure travel operations continue to concentrate on the Mediterranean, the Canary Islands and European leisure cities, which means that the business is becoming increasingly seasonal as it continues to grow and, as a result, increased losses are to be expected in the second half of the year," says Phillip Meeson, chairman of Jet2 owner Dart Group.
Load factors rose from 91.6% to 92.5% in the first half as passenger numbers outstripped seat-capacity growth of 12%.
Capacity for summer 2014 is to be raised a further 14% as the airline adds services from all of its bases.