Ryanair would offer captain salaries, consisting of basic pay and allowances, between £95,119 and £115,619, almost £11,000 more than Aer Lingus's £104,820 offer.
However, it is unclear what ancillary benefits will be on offer for high-ranking officers at Ryanair.A crucial element of the Aer Lingus pilots' package is its defined benefit scheme pension.
"You can't compare Ryanair and Aer Lingus," said the assistant general secretary of the IMPACT union, Michael Landers.
"What Ryanair calls a salary is made up of basic pay and the pre-tax equivalent of flight payments. We'll be having a look at its wage announcement, for what it's worth but I think we'll be taking it with a grain of salt."