Unite members employed at Heathrow will be on picket lines tomorrow (Tuesday 1 December) in the dispute over wage cuts.
Unite said it will be maintaining "three strictly socially distanced picket lines".
Unite recorded an 84% yes vote among its members at Heathrow, in opposition, Unite said, to "fire and rehire policies that will result in workers suffering permanent pay cuts of up to £8,000 per annum".
The strike action will involve firefighters, engineers, campus security, baggage operations, central terminal operations, landside and airside operations.
Unite regional co-ordinating officer Wayne King said: “Unite have tried to negotiate temporary pay cuts but Heathrow were simply not interested.
“The dispute will undoubtedly cause widespread disruption but it was taken as an absolutely last resort by members who simply can’t afford the cuts HAL (Heathrow) is imposing on them.”
Following the initial day of strike action there will be further strikes on Monday 14 December and then a two-day stoppage on Thursday 17 December and Friday 18 December.
A Heathrow spokesperson said: “It’s very disappointing that Unite has decided to take strike action during the worst crisis to hit the aviation sector.
“Our focus has been to protect jobs – which is why we’ve offered every frontline colleague who wants one a job at a market rate salary above the London Living Wage, even despite a loss of over £1.5 billion to our business so far this year.
“We do not believe this strike action is necessary, but have activated extensive contingency plans which will keep the airport open and operating safely throughout this period.”