Heathrow’s Terminal 5 saw long queues at security on Monday morning because of the absence of more than 100 staff, who were instructed to self-isolate by the NHS Test and Trace app.
Some passengers experienced lengthy queues from 06:00. Many complained that there was limited social distancing.
The disruption affected only Terminal 5 and did not involve border force officers.
Some passengers complained on Twitter about “total chaos” and posted pictures of large crowds at the terminal.
One passenger, Kathryn Wylie, was travelling to Glasgow when she was caught up in the disruption. “It was manic,” she told the BBC.
“In Terminal 5, both security queues were backed up, with little being done to move people forward who had the closest upcoming flights.
“Luckily, one lady came through handing out water, but I’m not sure that went on very long.
“Once you finally got through to the security screening, there were maybe only two to four of the belts functioning, which made the whole process even more drawn out.”