Travel firm Jet2 said it remained cautious in its outlook for next summer after falling to a pre-tax loss of £119.3m for the first half of the year.
With travel bans and quarantine restrictions in place for much of the six months to 30 September, the package holiday company swung from a £337m profit the year before.
The firm was forced to ground its planes from mid-March to mid-July due to the coronavirus pandemic, allowing some flights to take place.
But with the government swiftly knocking countries off its quarantine free travel list, it has flown just 1m passengers this summer, down from 10m the year before.
Jet2 initially tried to focus on popular holiday destinations such as Spain and the Canary Islands, but was soon forced to divert away from these.
It said that it expected further losses in the second half of the year, which coincides with the traditionally less profitable winter season.
Winter seat capacity is currently expected to be half of 2019 levels, Jet2 said.
But, with international travel banned under the current lockdown, it said that its “ability to fly in the short-term remains uncertain”.
Although recent announcements that not one but two vaccines have proved effective against the new disease, chairman Philip Meeson said the firm was still cautious over future prospects.
He added that current bookings for next summer were close to 2019’s levels already.