UK airline BMI British Midland has announced that up to 1,500 jobs are to go as part of a £100m ($166m) cost-cutting exercise over the next three years.
By Simon Montague
BBC transport correspondent
The staff reduction represents up to a third of the airline's 4,000 strong workforce, but BMI said it expected the job cuts could all be found through natural wastage.
Airport staff will be significantly reduced, as more passengers are encouraged to use automatic and remote check-in facilities.
The airline says it is facing the "toughest trading environment for a long time", with hopes of recovery delayed by the Iraq conflict and outbreak of the Sars virus.
BMI made a pre-tax loss of £19.6m last year and expects to make another, smaller loss this year.
The cost cutting exercise - called "Project Blue Sky" - will include the simplification of BMI's aircraft to an all-Airbus fleet, with the transfer of Boeing 737s to the airline's low cost subsidiary bmibaby.
BMI is also calling on the government to break up airport operator BAA's monopoly at Heathrow, if the airport gets clearance to build another runway.
The airline says a third runway and sixth terminal should be controlled by a different airport operator, in order to improve competition.
Last month BMI denied it had been in merger talks with Virgin Atlantic following speculation that the two carriers were considering a deal.
However, the airlines did confirm they had held discussions about closer co-operation on issues such as code-sharing - selling seats on each other's routes - and sharing facilities.