EasyJet, the Luton-based low-cost airline, warned its traditional first-half loss will be exacerbated this year by the later timing of Easter and the weakness in fares.
Historically, EasyJet has usually shown a loss in the first half of its financial year (to end-March) and has generated the majority of its profits in the last quarter of the financial year.
It cautioned that although current forward bookings are "robust", the overall profile of the last quarter's revenue, and hence the full year outcome, will not become apparent for "at least" several months.
"EasyJet continues to believe that its business model is robust and that it is well placed in the current environment to grow the business in line with its stated strategy," it said.
The airline's comments accompanied the release of its March traffic data. EasyJet carried 1.71 million passengers in March, a 32.2 per cent increase compared with 1.30 million in the year earlier period. This gave a rolling 12-month total of 18.6 million.
The figures are based on the combined data for easyJet and Go-Fly, the rival low-cost carrier it acquired last August.
EasyJet's March load factor - the number of passengers as a proportion of the number of seats available - rose to 85.8 per cent from 85 per cent.
In February passenger traffic had increased 43.9 per cent and the load factor was a record 88.7 per cent.
In the half year to March easyJet saw a 37.7 per cent increase in sectors flown with a load factor of 82.2 per cent, up from 81.1 per cent .
It said lower fares stimulated a 39.6 per cent growth in passengers. Overall, the average fare of £37.44 sterling for the six months was 10.7 per cent lower than last year.