The result of a union ballot that could lead to strike action at BAA airports this month will be revealed shortly.
The Unite union has asked 6,185 of its members who work for BAA to vote for strike action in a dispute over pay.
Unite has called BAA's pay offer of a 1% increase this year "paltry", but the company says it is reasonable.
BAA has confirmed its airports would have to close on any strike days. It owns Heathrow, Stansted, Glasgow, Edinburgh, Aberdeen and Southampton.
Staff being balloted include firefighters, security guards and engineers, who are essential for the day-to-day operation of an airport.
Members of the much smaller Prospect union, which represents about 100 BAA members of staff, have voted in favour of industrial action.
Prospect said 53% voted in favour of strike action while 83% backed action short of a walkout, such as an overtime ban.
Unite says BAA staff accepted a pay freeze in 2009 and has described the offer for this year - a 1% increase, with the possibility of an extra 0.5% if the union agrees to changes to the company's sickness agreement - as "measly" and "nothing short of confrontational".
The union is also calling for staff to receive a bonus, promised to them if the company met a certain earnings target.
BAA, owned by Spain's Ferrovial, missed the target by 3%. Unite says staff deserve financial recognition for coming so close.
Unite's national officers for civil aviation, Brendan Gold and Brian Boyd, said they had been in talks with BAA for months and were prepared to continue talking.
"A negotiated agreement can be reached if the company is prepared to be fairer and more realistic," they said.
BAA has said that it regrets the union's decision to ballot on strike action and that its offer is reasonable "at a time when BAA and its airline customers are seeing a decline in passengers due to the impacts of recession and volcanic ash".
Prime Minister David Cameron called on Unite to halt the threat of strike action.
"These sorts of strikes never achieve anything apart from damage - damage to the business, damage to the jobs, damage to the interests of the tourists who want to come to visit Britain, or people who want to leave Britain and have a holiday overseas," he said.
Unite is currently also in a dispute with British Airways, which has resulted in 22 days of strikes so far this year.
The union has threatened to ballot for further strikes starting in September.