BAA's earnings before tax and interest will be £1.3bn this year, 1.2 per cent lower than it previously forecast, as carriers switch to cleaner aircraft quicker than expected.
This is because the airports operator's income from landing fees is regulated by the Civil Aviation Authority, which forces it to charge less to airlines flying lighter or greener aircraft. But BAA will recover the cash in 2014, as the regulator sets out a fixed amount it can earn from both passengers and aircraft.
This year BAA reckons Heathrow, the world's busiest airport, pictured above, will again break records to handle more passengers than ever before.
In 1998, it flew 60 million people a year, but in just the first five months of 2012 more than 27 million people have passed through the London airport's arrivals and departures halls. Now BAA expects to hit 70.9 million passengers for the full year.
Although the airport is operating at full capacity in terms of flights, passenger numbers are growing as airlines fly bigger aircraft.
Most of Heathrow's growth has been driven by North Atlantic traffic, mainly due to the British Airways and American Airlines transatlantic tie-up and new Delta Air Lines routes.