Unite said ground services crew employed by Menzies Aviation at Edinburgh and Glasgow airports have overwhelmingly rejected “unacceptable” separate pay offers from the company.
The union warned that unless a better offer is tabled, it will have no option but to ballot members for industrial action.
Unite said around 300 Menzies Aviation workers, 97% of those balloted, rejected a basic uplift offer worth around 4.25% at Glasgow Airport, while at Edinburgh Airport, 100% of some 300 workers balloted rejected an offer worth around 4%.
Unite industrial officer Carrie Binnie said: “Summer strike action looms over Edinburgh and Glasgow airports because the pay offers on the table from Menzies Aviation aren’t good enough.
“Menzies Aviation has the ability to improve its offers and they can easily resolve this pay dispute without any disruption to the travelling public.
“If the company fail to table a better offer to our members, Unite will have no option but to ballot our members for strikes over the summer holidays.”
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The union said the workers – which includes dispatchers, allocators, airside agents and controllers – provide essential support for a host of major airlines.
Unite general secretary Sharon Graham said: “Unite’s Menzies members have emphatically rejected unacceptable pay offers.
“The Menzies group is posting sky-high profits and our members who contribute towards this success deserve far better from the company.”
Menzies Aviation was contacted for comment.