Virgin Atlantic has confirmed it has been forced to operate some near-empty flights after bookings were dented by the coronavirus outbreak.
It is operating the flights to try to retain take-off and landing slots at major airports such as Heathrow.
Under European law, if flights are not operated, slots have to be forfeited.
UK Transport Secretary Grant Shapps has written to the European Commission, asking for rules on slot allocation to be relaxed during the outbreak.
Other carriers are thought to be taking similar steps – even reportedly flying so-called “ghost planes” with no passengers on board at all in order to safeguard their presence at major hubs.
Airline passenger numbers have fallen dramatically in recent weeks due to the coronavirus outbreak. On some routes they have halved and carriers have been cancelling services.
However, this could cause them a serious problem, particularly if they fly out of large or heavily congested airports. Under international guidelines, which are enshrined in European law, take-off and landing slots at these airports are limited.
In the UK, the rules apply to Heathrow, Gatwick, Stansted, Manchester, London Luton and London City.
Slots are granted according to historical rights at these airports. If, for example, a carrier operated a particular schedule through the summer season last year, it retains the right to those same slots this summer.