Airline Norwegian suffered a 61% drop in demand last month.
The budget carrier said it carried 1.2 million passengers in March, compared with 3.0 million during the same month in 2019.
Norwegian chief executive Jacob Schram said: “The speed of the Covid-19 global outbreak throughout March had a profound impact on the entire Norwegian network as cancellations, in line with global travel advice and falling demand, were implemented throughout the month.”
The Scandinavian airline reduced its flight schedule several times last month in response to the collapse in demand caused by the coronavirus pandemic.
This culminated in capacity being cut by up to 85%.
Some 7,300 staff members have been temporarily laid off by Norwegian, which equates to 90% of its workforce.
Norwegian usually carries almost six million UK passengers each year from Gatwick, Manchester and Edinburgh airports to 30 destinations worldwide.
It has shaken up the long-haul market by offering flights at knockdown prices, with some of its most popular deals including £99 transatlantic trips to New York.
But the airline’s finances have struggled amid its rapid expansion, and in recent years it has been forced to cut costs to regain profitability.
All airlines have suffered as a result of Covid-19, with British Airways, easyJet and Ryanair among those serving the UK which have grounded the majority of their fleets.
But campaigners and organisations have warned governments to resist rushing into “unfair” bailouts of the sector under pressure from aviation lobbying.
Some 250 organisations from 25 countries are calling on governments to bail out workers, rather than shareholders and executive, and transform the transport sector in a climate-friendly way by cutting air travel demand and strengthening low-carbon alternatives such as rail travel.
They are also calling for an end to aviation’s tax exemptions as well as putting in place a kerosene tax and “fair progressive levies” on frequent flying.
Leo Murray, director of innovation at UK climate action charity Possible, said: “At this time of crisis, we need to focus on what’s most important: protecting ordinary people and building a more secure future for all of us.
“Rather than bail out airlines to continue with business as usual, we now have a chance to ensure that they change for the better.”
He said that, in return for government support, airlines must protect their workers and protect the climate by reducing the sector’s emissions in line with international targets to limit global warming to 1.5C.