Ground operations staff at Aer Lingus, who are members of SIPTU, have overwhelmingly rejected a cost-cutting plan.
Balloting concluded on the Company Covid Recovery document earlier today.
The document was rejected by 82% of those who voted across both contract types.
This comes after Aer Lingus told cabin managers that a number of staff would be temporarily laid-off and that pay cuts would not be partially restored as hoped.
It follows the strong rejection of proposed cabin crew work practice changes in a ballot earlier last week, conducted by the Forsa union which represents them.
SIPTU represents around 1,100 workers employed by Aer Lingus as ground crew in Dublin Airport.
In a statement released this evening, SIPTU Sector Organiser, Niall Phillips, said: "Prior to this ballot, union representatives and organisers engaged with management at the company concerning changes it wished to implement due to the losses the company incurred during the Covid-19 pandemic. Our members have clearly rejected what was proposed to them.
"Workers in the aviation sector have been severely affected by the Covid-19 crisis. Many have been laid off for long periods of time, others saw significant reductions in their working hours and hundreds have been made redundant across the sector," said Mr Phillips.
SIPTU TEAC Division Organiser, Karan O Loughlin, said: "While the majority of our members in Aer Lingus who rejected this proposal continue to work at 80% of their normal hours, we can't forget that there are many others still on short-time work or lay off.
"Our members accept that the aviation industry suffered significant losses due to the pandemic but so did its workers. They believe that this [has] not been adequately recognised by the company. The only way for a meaningful recovery in Aer Lingus is for both workers and the company to have the same opportunity to recover."