Heathrow is to extend a cap on the number of passengers flying from the airport until the end of October due to staff shortages.
It means the limit will now be in place until after the UK school half-term holidays.
After consulting with airlines, a daily limit of 100,000 departing passengers will now apply until 29 October, the airport said.
It said the measure would enable more reliable passenger journeys.
The airport also said the cap would be kept under regular review and could be lifted early if staffing levels improved.