You need to do your homework, this strile has noting to do with DAA staff over the pension issue. Its only Aer Lingus. Both company's have the problem with pensions but as usual Aer Lingus staff go on strike.
The reason being that the DAA agree a settlement with the pension fund. EI added conditions to their help, they want their staff to take an unspecified payfreeze and increase productivity. Which pretty much much means EI want their staff to inject their own work/money cash into the fund. They also refused to go to the Labour Court for arbitration on the matter.