Passenger numbers have dropped at privately-owned airline BMI since it axed free food and business-class cabins on many of its flights.
BMI's new strategy may have come at a price
The company confirmed there had been a fall in passenger numbers after figures leaked to the Guardian newspaper showed a dramatic slump.
As well as changes in policy the airline blamed competition from low-cost rivals.
BMI declined to give further details ahead of its annual profits statement.
But it did say it had changed its strategy to concentrate on delivering value rather than volume of passenger numbers.
BMI flights from Heathrow carried 13% fewer people in February than they did a year ago, the Guardian reported.
Routes between London and Scotland suffered the biggest slump in passenger numbers, with Glasgow traffic down 24% and Edinburgh falling 17%.
However, chief executive Nigel Turner said BMI would produce encouraging results when it announces its annual profits next week.
"We've taken a different strategy since I became chief executive," Mr Turner told the Guardian.
"We have specifically focused on getting smaller aircraft in. We have been concentrating on yield (price) and concentrating on business passengers. We have cut out a bunch of uneconomic fares."
But eyebrows are likely to be raised over the strategy, launched last May, which saw free food and business-class cabins abolished on many of its flights.
BMI also revamped its pricing structure, offering three types of ticket depending on the level of service required.
The passenger figures could heighten speculation about BMI's future as an independent company.
Chairman Sir Michael Bishop has a controlling stake of just over 50%.