By David Stewart White
The Services, Industrial, Professional and Technical Union (SIPTU), which represents Aer Lingus employees, has been embroiled in a fight over pensions for airline workers. The Aer Lingus pension scheme is underfunded.
A strike at regional affiliate Aer Arann was avoided in August.
Aer Lingus is Ireland's largest airline. It primarily serves Europe and also has limited service to and from the United States.