British Airways has around 3,000 potential recruits stuck in background checks that are taking up to four months, it said at a parliamentary hearing into the travel chaos gripping UK airlines and airports.

Appearing before the House of Commons transport committee Tuesday, executives from BA, EasyJet Plc and TUI AG provided details of staff shortages they say are to blame for the delays and cancellations. EasyJet said it has 140 crew trained and ready to go who don’t yet have the required airside passes.

The airlines said requirements for five years of reference checks are also slowing down hiring, with many candidates having a rather more checkered employment history after the coronavirus forced them to take short-term roles. Aviation minister Robert Courts said he’s worked on the issue with the travel sector and that people will now be able to provide a letter stating their working history, rather than approaching each of their prior employers.

While travel hubs across Europe have struggled to cope with an influx of vacationing passengers, the UK has been especially hard hit and airlines have faced accusations that they let go too many staff during the pandemic and have been too greedy in setting summer schedules.

The school holidays and Jubilee weekend in early June saw long lines at airport security, leading to missed journeys, coupled with chaotic and potentially dangerous scenes as returning passengers sought to recover their own bags after they failed to appear on carousels hours after landing. Airlines have also canceled hundreds of flights in advance as they struggle to recruit.

David Burling, TUI’s chief executive officer for markets and airlines, said the world’s largest tour operator, which scrapped UK flights over the break, has now contracted extra aircraft and cabin crew. It has also added customer service personnel, though some of those are awaiting security clearance.

IAG SA-owned British Airways, which has canceled the most flights among the three operators, is working to rebuild trust with staff and customers, Corporate Affairs Director Lisa Tremble said. EasyJet Chief Commercial Officer Sophie Dekkers said the discounter “hadn’t got it right and we need to get it right.”

Following the hearing, the Civil Aviation Authority and Department for Transport sent a joint letter setting out expectations that include an airline review of schedules to guarantee that they’re “deliverable,” and a requirement for airports to establish working groups to ensure they’re running smoothly.