Residents who are living on the Heathrow flight path say they are dismayed that the cap on the number of flights allowed to use the airport each year could be lifted.
Heathrow chairman Lord Deighton told The Times the airport might apply for it to be lifted for the four years before a third runway opened - if it was given the go-ahead.
At present up to 480,000 flights are allowed to use Heathrow each year.
The limit was set in 2001 as part of the agreement which allowed Terminal 5 to be built. However, the actual number of flights using the airport has hovered around 475,000 for the last few years.
Lord Deighton told the newspaper an additional 50 flights a day could use the airport and that the move was needed to show Britain was "open for business" after Brexit.
But John Stewart, chair of the Heathrow Association for the Control of Aircraft Noise (HACAN), said, "Residents will be dismayed at losing the protection the cap has brought.
"If it is introduced in advance of a third runway, the third runway mitigation measures must also be brought forward."
He explained that if the cap was lifted, HACAN would be pressing for key measures to be introduced, including a tougher night flight regime, the release of the £700 million promised to improve insulation of properties under the flight paths, and a guarantee that the runway alternation currently available to residents in west London will remain