Thousands of workers at some of the country's biggest airports will today start voting on whether to launch a campaign of industrial action over pay, threatening disruption before the end of the summer holidays.
Unite said 6,000 of its members who work as firefighters, engineers and support and security staff at Heathrow, Stansted, Southampton, Glasgow, Aberdeen and Edinburgh will vote over the next few weeks over a "measly" offer.
The union said airport operator BAA is only offering a 1% pay rise, plus 0.5% conditional on changes to the sickness agreement.
Workers can also earn a bonus if BAA meets financial targets, said Unite.
Unite's national officer for civil aviation, Brendan Gold, said: "BAA's measly pay offer is nothing short of confrontational.
"Last year, staff accepted a pay freeze. Their generosity helped the company, yet BAA has returned the favour with no bonus and a 1% pay offer when inflation is currently 5%."
Unite officer Brian Boyd added that negotiations had been held for months and Unite is prepared to continue talking because an agreement could be reached if the company is prepared to be "fairer and more realistic".
The strike ballot will close on August 12.