Heathrow’s passenger numbers were down 81% in September, figures published by the airport show.
Just 1.3 million people travelled through the west London airport last month, compared with 6.8 million in September 2019.
More than half of the passengers who used Heathrow last month were flying to or from the European Union.
Heathrow said long-haul business travel continues to be restricted by international border closures and “a lack of testing” for Covid-19.
Last week, the Government unveiled a taskforce to develop a coronavirus testing system as a potential way of easing quarantine restrictions for arriving passengers.
Heathrow chief executive John Holland-Kaye said: “The Government’s Global Travel Taskforce is a great step forward, but needs to act quickly to save the millions of UK jobs that rely on aviation.
“Implementing ‘test and release’ after five days of quarantine would kickstart the economy.
“But the Government could show real leadership by working with the US to develop a common international standard for pre-departure testing that would mean that only Covid-free passengers are allowed to travel from high-risk countries.”