Global air passenger traffic plunged by an unprecedented 66 percent in 2020 owing to travel restrictions imposed during the Covid-19 pandemic, an industry group said Wednesday.

The International Air Transport Association (IATA) also warned that new, more transmissible variants of the coronavirus could hurt prospects for a recovery this year.

Given that travel restrictions have been applied mostly to international travel, domestic passenger traffic fared better, falling by 49 percent, compared with 76 percent for foreign passenger traffic.

Travel restrictions imposed during the first wave of the pandemic caused global passenger traffic to reach just five percent of its normal level, with airlines parking planes on runways because no other space was available.

"Last year was a catastrophe. There is no other way to describe it," an IATA statement quoted Director General Alexandre de Juniac as saying.

"What recovery there was over the Northern hemisphere summer season stalled in autumn and the situation turned dramatically worse over the year-end holiday season, as more severe travel restrictions were imposed in the face of new outbreaks and new strains of COVID-19."

IATA chief economist Brian Pearce told a video news briefing: "Overall, global passengers kilometers flown were down two thirds, this is the biggest shock the industry of air travel has ever experienced."

IATA, which represents 290 airlines, did not formally lower its outlook for a pickup in traffic this year thanks to a global rollout of vaccines, but warned that the emergence of new variants of the virus clouded the forecast.

And "we begin 2021, which we still expect to be a year of recovery, from a very low point," Pearce noted.

The association officially expects traffic to increase by 50 percent from last years levels, but that would still represent just half of the result seen in 2019.

- 'Challenging outlook' -
And "the proliferation of restrictions on travel that we have seen since the beginning of the year could make even that modest outlook very challenging," de Juniac told the press briefing.

"We are eager to work with governments as partners to understand what the benchmarks and conditions will be for a decision to give people back their freedom of movement," he added.

One relative bright spot last year came from air freight, which declined by a relatively modest 10.6 percent from the 2019 level as measured in cargo tonne-kilometers, or CTKs.

That was nonetheless the worst drop since IATA began using the measure in 1990.

As a result, global airlines suffered a combined loss of $370 billion last year, according to data compiled by the UN aviation agency ICAO.