Heathrow was showing 31 cancelled flights to and from the United States by 9.45am on Saturday 14 November, up from 29 three hours earlier, with around 20 further departures delayed, as the UK's aviation regulator warned passengers to expect continued disruption even though US airspace has reopened.
The cancellations are the knock-on effect of an unprecedented nationwide ground stop ordered by the US Federal Aviation Administration on Friday, which halted all domestic departures across the continental United States for more than four hours, from 15:54 to 20:15 US Eastern time (19:54 GMT to 00:15 GMT). The FAA said the shutdown followed a telecommunications and radar problem affecting air traffic control systems, caused by new technology overwhelming outdated equipment, according to the BBC. Officials said there was no evidence of a cyber-attack. More than 15,000 US flights were delayed or cancelled, affecting an estimated 1.5 million passengers, making it the most disruptive such stoppage since the 9/11 attacks in 2001.
US Transportation Secretary Sean Duffy confirmed shortly after 1.30am GMT on Saturday that US airspace had reopened, but said the ripple effects would continue for a number of days as airlines work through a backlog.
At Heathrow, the Evening Standard reported that by 9.45am on Saturday the airport's own departure board was showing 31 cancelled flights for the day, including British Airways, American Airlines, United Airlines and Delta Air Lines services to and from New York, Chicago, Dallas, Houston, Los Angeles, Atlanta, Miami, Raleigh and Charlotte. A further 20 Heathrow departures were delayed. At Gatwick, three arrivals from Orlando, operated by British Airways, American Airlines and Iberia, were cancelled.
The UK Civil Aviation Authority has formally warned travellers of what it called follow-on disruption. Tim Johnson, the CAA's consumer director, said: "While US flights have resumed, there may be some follow-on disruption as airlines work to re-book affected passengers and get all services back to normal. Anyone due to travel on flights between the UK and USA should check with their airline for the latest information before heading to the airport."
British Airways has advised passengers to still travel to the airport for their original departure time unless told otherwise, saying its US-bound flights may be delayed due to the ongoing air traffic control issue, and that the situation is entirely outside of its control. Virgin Atlantic also confirmed a Heathrow to New York JFK flight was cancelled and urged customers to check their flight status online.
What this means for your journey: if you are flying to or from the US via Heathrow in the coming days, check your flight status directly with your airline before leaving home and build in extra time at the airport while airlines work through rebookings. See our public transport guide for getting to the terminals without adding to the uncertainty.