Travellers were unable to check in baggage at Heathrow Terminal 5 this morning due to a computer glitch.
Problems started at around 9am and lasted until 11.30am.
The airport said the problem had been resolved, but some passengers faced long queues and delays, the BBC reported.
An airport spokesman said: “Our teams have now restored all check-in services and we have additional staff in the terminal to help passengers.”
Heathrow said passengers with hand luggage only were unaffected, but others were prevented from checking in and unable to travel.
A British Airways spokesman apologised for the inconvenience and said “all of our flights continue to operate as normal”.