Ryanair boss Michael O'Leary has hit out at Aer Lingus for failing to reign in unions.
Mr O'Leary's criticism comes as 1,200 cabin crew members hold a 24-hour work stoppage over rostering at the airline.
Up to 30,000 passengers have been affected, with talks set to take place between unions and management next Wednesday.
Michael O'Leary said Aer Lingus should never have let the strike happen. The airline is also calling for ICTU boss David Begg to resign as non-executive director of Aer Lingus.
"When the Government appoints one of the big trade union bosses to the board of Aer Lingus, what chance have you got?" he said. "That's why the board of Aer Lingus is incapable of dealing with these issues.
"The company should be out there explaining its case to the public, why the cabin crew don't have any genuine grievance and why this is just public sector unions holding a section of the public to ransom."