Cancellations and diversions leave thousands of passengers stranded as airlines scramble for alternatives.

Travel plans for thousands of passengers were thrown into chaos on 21 March as at least 11 flights between Singapore and London faced cancellations or diversions following the sudden closure of Heathrow Airport. The UK’s busiest airport announced it would remain shut until midnight due to a major power outage caused by a fire at a nearby electrical substation.

Of the affected flights, six were cancelled. Singapore Airlines (SIA) confirmed that flights SQ305, SQ317, SQ319, and SQ321—scheduled to depart from London—were among those cancelled. Additionally, flight SQ318, which was set to leave Singapore at 12:45pm, did not take off. Flight SQ308, which had already departed, was forced to return and is expected to land back in Singapore at 4:30pm.

To assist impacted travellers, SIA stated that it would provide hotel accommodation and arrange alternative flights or transport where possible. Several flights were redirected to other European airports. SQ322, which left Singapore on 20 March, was rerouted to Frankfurt, while SQ306, departing on 21 March, was diverted to Paris-Charles de Gaulle.

Qantas Airlines also faced disruptions, with flight QF1 heading to Paris instead of London. The airline has arranged buses to transport passengers on an estimated nine-hour journey to their final destination. Meanwhile, QF2, originally set to leave Heathrow for Singapore on 21 March, is likely to be impacted as well.

British Airways confirmed that flights BA12 and BA16, departing Singapore on 20 and 21 March, were redirected to Gatwick Airport. A spokesperson stated that the airline is working to update passengers regarding travel arrangements over the next 24 hours.

Changi Airport Group (CAG) advised passengers travelling between Singapore and London to check their flight status directly with airlines. Information on departures and arrivals can also be found on CAG’s website.

Among the many stranded travellers, 26-year-old Ashley and her mother, who had been holidaying in London, were scheduled to return on SQ321. Informed of the cancellation early in the morning, they are now considering taking a train to Brussels to catch an alternative flight to Singapore. “I’m quite stressed because I start a new job on Monday, but I’ll figure things out tomorrow,” she shared.

The fire that caused the power outage at Heathrow led to widespread disruption, with Heathrow officials warning that the situation may persist for days. Emergency crews are working to restore power, but there is no clear timeline for when normal operations will resume.

According to flight tracking services, at least 120 flights are being redirected due to the closure. Diversions include Qantas’ Perth flight landing in Paris, a United Airlines flight from New York being rerouted to Shannon, Ireland, and another United flight from San Francisco now scheduled to land in Washington instead of London.

Heathrow, ranked the world’s fifth-busiest international airport in 2025, is expected to face continued disruption as airlines and passengers seek alternative travel plans.