All British Airways short-haul flights from Heathrow were cancelled until at least midday on Saturday due to a computer glitch.
The problem, coinciding with the end of school half term holidays in parts of the country, was not a cyber attack but related to a hardware issue the airline.
The airline’s website was working and passengers with cancelled flights were offered a refund or rebooking options.
But the knock-on impact lasted throughout the day and into Sunday. The airline declined to disclose the number of flights affected.
BA expects to return to running a normal schedule today.
A BA spokesperson said that “technical issues” meant all short-haul flights from Heathrow were cancelled on Saturday until midday.
Long-haul services at Heathrow and all flights at Gatwick and London City Airport were due to operate as planned, but with some delays.
“We are offering customers on cancelled services options including a full refund and all customers booked to travel on short-haul services from Heathrow [on Saturday] can opt to rebook to a later date for free if they choose. We will be contacting customers proactively,” the spokesperson said.
“We know we have let our customers down and we will do everything we can to make this up to them.”