British Airways, easyJet and Tui are using an employment loophole to operate flights with EU crews without British work visas, as they grapple with staff shortages.
The airlines are borrowing EU-registered aircraft under so-called wet leasing agreements as they grapple with some of the worst staff shortages on record.
The practice means they can circumvent post-Brexit immigration rules that would otherwise prevent airlines from running flights with EU staff without a British employment visa.
British Airways has borrowed four aircraft from Finnair and four from sister airline Iberia instead of using any of 18 UK-registered Airbus planes the flag carrier has in storage, according to industry sources.
EasyJet has “wet leased” eight aircraft to operate out of Gatwick and one out of Bristol from Latvia’s SmartLynx Airlines.
Tui is borrowing five of SmartLynx’s jets to run services out of Gatwick, Manchester and Doncaster airports, as well as two planes from Lithunian airline Avion Express for flights out of Gatwick.
Grant Shapps, the Transport Secretary, has so far resisted demands from airlines, airports and ground handling companies to allow an influx of foreign workers to ease a staffing crisis that has caused misery at UK airports this year.
Bosses want the Government to consider offering temporary visas similar to those issued to fruit pickers, musicians and religious figures to fill gaps in the workforce.
Airlines leaders are understood to have warned officials from the Department for Transport during a call last Friday that carriers will run increasing numbers of overseas-flagged aircraft with only a skeleton number of UK-registered jets if ministers do not relax immigration laws.
It is estimated that more than 2.5m passengers will fly in and out of the UK across the three airlines’ aircraft that are registered overseas and crewed by overseas staff.
The airlines said “wet leasing” is a common industry practice. There is no suggestion that it is breaking any of the UK’s immigration laws.
A source at one airline said it is not a viable way to get European labour into the UK as it is a lot more expensive and “merely a back-up measure where the industry has short term capacity needs.”
Another disagreed, saying it was not always more expensive — instead it is dependent on supply and demand of surplus aircraft among rival airlines.
A spokesman for British Airways said: “To offer our customers access to as many destinations as possible, our partner airlines are operating some European flights for us as we continue to rebuild our operation.”
EasyJet and Tui declined to comment.
Mr Shapps is, however, considering whether to relax rules that prevent airlines from cutting their timetables at capacity constrained airports such as Heathrow and Gatwick, where take-off and landing slots are highly sought after and worth tens of millions of pounds each.
The Transport Secretary has already criticised carriers for selling seats on flights that they were unable to operate.
Officials from the DfT this weekend released an emergency consultation on “70:30 rules” this summer. It would mean airlines must operate 70pc of their flights at capacity-constrained airports or hand back the slots to an industry coordinator.
Airlines were handed the consultation last Friday and given until Monday to respond, according to an industry source.
Last week Gatwick restricted the number of flights that can take off and land at the airport for the first time in its history to address same-day cancellations by airlines.
It is putting in place a cap of 825 in July and 850 in August, meaning as many as 4,000 flights will need to be cut, disrupting summer holidays for hundreds of thousands of Britons.