Heathrow remains committed to expanding the airport via a third runway, but has warned the project will likely be delayed by "at least two years" due to the coronavirus crisis.
In a first quarter trading update, Heathrow revealed Q1 passenger numbers fell 18.3% to 14.6 million, while April passenger numbers are expected to come in 97% down on last year.
"We expect passenger demand will remain weak until governments around the world deem it safe to lift travel restrictions," said the airport, adding daily passenger numbers "have shrunk to the thousands".
Heathrow chief executive John Holland-Kaye has meanwhile called on the UK government to lead talks over a set of "international standards" for safe air travel fit for the post-coronavirus world.
"When we have beaten this virus, we will need to get Britain flying again so the economy can recover as fast as possible," said Holland-Kaye.
"That is why we are calling on the UK government to take a lead in setting a common international standard for safe air travel."
He said the hub, Britain’s busiest airport, was working with partners around the world to develop these guidelines.