The Airport Operators Association (AOA) said nearly £2bn was lost in the four-month period between March and June alone, which is equivalent to around £15 million each day.
It anticipates that the finances of its members will continue to suffer throughout the rest of the year, putting up to 110,000 jobs at risk at airports and their supply chains.
Passenger numbers have fallen by as much as 99 per cent during the crisis, with demand for travel collapsing and restrictions being introduced by governments around the world.
Heathrow said just 350,000 people travelled through the airport last month, down 95 per cent on June 2019.
ACI Europe, which represents European airports, recently predicted that passenger numbers will not recover until 2024.
The AOA and airport chief executives have written to Prime Minister Boris Johnson calling on him to take urgent action to help the aviation industry.
They noted that the aviation industry has been “denied the kind of targeted support afforded to other sectors”.
The AOA wants relief from business rates for 2020/21 in line with support given to the hospitality and retail sectors, help with meeting employment costs when the furlough scheme ends, and the suspension of Air Passenger Duty for at least six months to stimulate demand.
AOA chief executive Karen Dee said: “These projections reinforce the significant challenges that UK airports continue to face after the worst four months in the history of commercial aviation.
“Whilst we have seen passengers begin to return, passenger numbers are not expected to reach pre-Covid levels for a considerable period and airports will continue to face challenges and pressures unimaginable six months ago.
“Airports have done everything in their power to weather the storm and have done so without the specific Government support afforded to other sectors.
“That our airports lost close to £2bn during the lockdown should serve as a wake-up call to Government and lead them to finally grasp the severity of the challenge and threat that the pandemic has posed and continues to pose to the sector.
“We cannot have a full national economic recovery without a thriving aviation sector.”
Earlier this week Edinburgh Airport warned it was “unavoidable” that around a third of jobs could go as it struggles with the economic impact of the coronavirus lockdown.
In a joint letter with Unite the Union, the airport warned First Minister Nicola Sturgeon that up to 2,000 of the 7,000 jobs on the campus could vanish as a result of the looming recession and a reluctance by the travelling public to fly, with a similar fraction of the 21,000 jobs supported by the airport’s supply chain also be at risk.