Airlines using Heathrow have been asked to cut 30 flights from this morning’s peak schedule to relieve pressure on its terminals.
A total of 1,200 flights were scheduled to leave throughout today (Thursday).
But the London hub is expecting more passenger numbers than it can currently cope with.
The airport claimed the cancellations were needed for both safety and to ensure as many passengers as possible catch their flights.
A similar number of flights were cancelled earlier this month because of a glitch in baggage handling equipment.
The ‘schedule intervention’ came as the UK aviation industry faces 40 years of passenger growth in just four months, stretching the entire sector as work goes on to scale-up operations as quickly as possible.
A spokesperson said: “We are expecting higher passenger numbers in the morning peak than the airport currently has capacity to serve, and so to keep everyone safe we have asked airlines to remove 30 flights from the morning peak.
“We will work with airlines to get affected passengers rebooked on to other flights outside of the peak so that as many as possible can get away, and we apologise for the impact this has on travel plans.
“We are working hard to ensure everyone has a smooth journey through Heathrow this summer and the most important thing is to make sure that all service providers at the airport have enough resources to meet demand.”
Rory Boland, editor of Which? Travel, said: “Heathrow knew how many passengers were due to fly from the airport weeks ago, so there is absolutely no excuse for it to be ordering on-the-day flight cancellations. These last-minute cancellations are hugely upsetting for travellers.
“British Airways and any airline forced to cancel journeys must inform customers of their refund and rebooking rights, including alternative flights with rival carriers, if that is the best option.
“Airports and airlines need to be held to account for the unacceptable disruption travellers have faced in recent months. Reform of travel rules is desperately needed, and the government should give the CAA direct fining powers so it can properly hold operators to account and drop plans to slash passenger compensation for delayed and cancelled domestic flights.”