All British Airways flights from Heathrow and Gatwick have been cancelled due to a computer system failure.On one of the busiest UK travel weekends of the year, BA have told passengers not to arrive at the airport for flights scheduled before 6pm BST on Saturday to ease congestion. However, there is no guarantee that flights after this time will depart as scheduled.The airline released a statement blaming an “IT systems outage”.“We are extremely sorry for the inconvenience this is causing our customers and we are working to resolve the situation as quickly as possible. Because we are experiencing issues with Heathrow and Gatwick, that is having a knock-on effect at airports worldwide.”The airline said there is “no evidence that it’s a cyber attack”Images on social media show BA staff having to settle with writing gate information on whiteboards. Blog Chaos at Heathrow – BA system problems apparently so severe that staff having to write gate information on white boards (pic: @theboyg) pic.twitter.com/0nGX16QH5F— Stephen Jones (@SteveJonesPA) 27 May 2017 May 27, 20170 Comments British Airways flights grounded amid major IT glitch There are reports of British Airways flights landing at Heathrow and Gatwick airports but not able to taxi to the terminal, as outbound aircraft cannot vacate the gates. This has resulted in passengers being stuck on aircraft for many hours.The airline said that all passengers will be offered the option of rescheduling or a refund.