The disruption began on Friday night and continued throughout Saturday, with flights cancelled or delayed as the impacted airlines had to carry out check-in and boarding operations manually. Heathrow said on Sunday that passengers should check their flight status before travelling to the west London airport. “We apologise to those who have faced delays, but by working together with airlines, the vast majority of flights have continued to operate. “We are actively working to resolve the issue and restore full functionality to our customers as quickly as possible. “The commission is working closely with EUROCONTROL, ENISA, airports and airlines to restore operations and to support passengers.