British Airways is working to restore its computer systems after a power failure caused major disruption for thousands of passengers worldwide.
The airline is “closer to full operational capacity” after an IT power outage resulted in mass flight cancellations at Heathrow and Gatwick.
Thousands of passengers remain displaced, with large numbers sleeping overnight in terminals.
BA has not explained the cause of the power outage.
So far today, 13 short-haul flights at Heathrow have been cancelled.
Chief executive Alex Cruz has posted videos on Twitter apologising for what he called a “horrible time for passengers”.
But no-one from the airline has been made available to answer questions about the system crash, and it has not explained why there was no back-up system in place.
Cancellations and delays affected thousands of passengers at both Heathrow and Gatwick on Saturday.
All flights operated from Gatwick on Sunday but more than a third of services from Heathrow – mostly to short-haul destinations – were cancelled.