British Airways is reported to have cut flights on its prime New York route over the summer peak, in a move that appears to undermine arguments for a third runway at Heathrow.
The airline, which has more than half the take-off and landing slots at Heathrow, dropped one return a day to John F Kennedy or Newark airports between mid-July and mid-September, the Sunday Times reported.
BA also cancelled other daily transatlantic flights, to Boston and Philadelphia. The airline has also dropped a number of daily short-haul flights to destinations including Zurich, Geneva and Aberdeen.
It carefully alternated which New York flight it dropped to avoid losing the right to operate the valuable slots. These must be used 80% of the time and can change hands for up to £40m a pair.
BA told the newspaper that the New York cancellations were intended to keep the rest of its schedule on track.
But aviation sources suggested that they indicate the airline may have too many slots at Heathrow and be over-scheduling routes, according to the report.
Heathrow says the airport is full to capacity and it needs a third runway, but BA argues that there is no justification for expansion.
The airline also suffered punctuality problems on several routes in July, with only a third of flights to Los Angeles and Las Vegas taking off on time.
BA said it revised the schedule during its busiest ever summer to give it “more breathing space” and offered passengers alternative flights. It blamed punctuality problems on air traffic control delays.