Anti-expansion campaigners last night poured scorn on BAA's promise to listen to the advice of an independent environmental watchdog if the third runway at Heathrow goes ahead.
Airport bosses announced yesterday they would be willing to accept the recommendations of a government-appointed assessor to check noise and air quality limits and set the number of flights at the airport.
The move comes amid a huge amount of criticism from locals and campaigners and only weeks before an expected decision.
Colin Matthews, chief executive of BAA, said: "We have listened to the many arguments around expansion at Heathrow.
"Although the economic case remains compelling, we understand that we can only increase the number of flights if we can safeguard levels of noise and air quality.
"By calling on an independent assessor to scrutinise the airport's performance against these limits, we are providing an uncompromising assurance that we will operate Heathrow airport within the limits laid down by the government.
"If we don't, the number of flights in an out of Heathrow could be capped."
Mr Matthews (pictured) also said BAA planned to use runways for 'mixed-mode' take-offs and landings a only at peak times and only after the record on flight delays has been improved.
But Ruth Cadbury, Labour councillor for Brentford, said: "I think it's a crazy idea given how environmental limits have already been set.
"I don't have any faith that his statement actually means anything. A third runway means the destruction of hundreds of communities and misery for those living under the flight path.
"Collin Matthews appears to have forgotten past promises that BAA have failed to act upon. If we can't trust him, how can we trust an environmental watch dog?
"Mixed mode is the thin end of the wedge for hundreds and thousands of residents living under the flight path. Our only respite is runway alternation, at least then we know when the noisy periods will be."
If BAA wins the battle for a third runway the annual number of inward and outward flights will increase from 480,000 to 605,000 by 2020 and 702,000 by 2030.