Heathrow has started consulting with unions over pay cuts in a process which could lead to job losses.
The west London airport said in a statement that its proposal “guarantees a job” for anyone who wants to remain with the business.
Around 4,700 workers across engineering, air-side operations and security roles are affected.
Heathrow’s plan involves around half having their salary reduced by approximately 15-20%, the PA news agency understands.
If no agreement is reached, then job cuts could be implemented.
Heathrow has already reduced its managerial roles by a third, and in June launched a voluntary redundancy scheme.
The airport said in a statement: “Covid-19 has decimated the aviation industry, which has led to an unprecedented drop in passenger numbers at Heathrow, costing the airport over