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.
Q1 revenue fell 12.7% to £593 million, and adjusted earnings before interest, tax, depreciation and amortisation by 22.4% to £315 million.
Heathrow said it had reduced costs by "around 30%" through cutting management pay, renegotiating all contracts and consolidating operations across just two terminals and a single runway.
Capital expenditure, meanwhile, has been cut by £650 million.
Despite the "catastrophic impacts" of coronavirus, Heathrow insists it remains on firm financial footing with around £3.2 billon in liquidity – "sufficient to maintain the business at least over the next 12 months, even with no passengers".
Holland-Kaye added Heathrow had been taking steps over the past decade to "beef up" the airport’s "financial resilience".
However, he warned Heathrow "was not immune" to the crisis. "The cost savings we are making now will help us to secure as many jobs as possible while maintaining the agility to return to growth when passenger demand increases."
The airport also said while it remains committed to expanding via a third runway, the project – due for completion by 2026 – will likely now be delayed "by at least two years".
"Expanding Heathrow remains a key plank of our long-term strategy once we have beaten Covid-19 and entered the recovery phase," said the airport in its trading update.
"However, given the current Covid-19 crisis and the ongoing appeals process [against expansion], we expect expansion and related capital investment to be delayed by at least two years."