EXCEPTIONAL summer season trading saw revenues at Jet2.com airline and package holiday operator Dart Group break the A 1 billion barrier for the first time in the six months to the end of September. The owner of Yeadon-based leisure airline Jet2.com, which has a training centre in Bradford, and package holiday operator Jet2holidays, boosted sales by 14 per cent to A 1.02 billion against A 902.2 million a year earlier.