The west London airport said it is continuing to lose money despite reducing its operating costs by more than 30%.
But it insisted it has the “financial strength” to survive “until the market recovers”, with £4.1 billion of cash.
Some 10.2 million passengers travelled through Heathrow in the first nine months of the year, compared with 19.0 million during the same period in 2020.
Proposals announced by the Civil Aviation Authority (CAA) last week to allow the airport to increase passenger charges by up to 76% “do not go far enough to ensure financeability”, Heathrow claimed.
The CAA is planning to raise the cap on the average charge per passenger over the next five years to between £24.50 and £34.40.
Heathrow had called for the range to be between £32 and £43. The current average charge is £19.60.
The airport’s chief executive John Holland-Kaye said: “We are on the cusp of a recovery which will unleash pent-up demand, create new quality jobs and see Britain’s trade roar back to life – but it risks a hard landing unless secured for the long-haul.
“To do that, we need continued focus on the global vaccination programme so that borders can reopen without testing; we need a fair financial settlement from the CAA to sustain service and resilience after 15 years of negative real returns for investors; and we need a progressively increasing global mandate for sustainable aviation fuels so that we can protect the benefits of aviation in a world without carbon.”