This is not to bash anyone, but Lots of employees who end up working for/at airlines; majority of pilots, probably all mechanics, air waiters, & ground staff simply don't understand the economics involved in running and ensuring an airline stays profitable, and how to ensure that they have a pension plan when they retire.
Problem is, very few pension funds were ever funded properly. Back in the day the acturial calculations weren't taking into account the length of time that todays retiree was going to spend drawing their pension.
Employers just promised jam tommorrow and paid peanuts for it, it was in no one's interest to examine things more closely - especially the execs as they expected to parachute out after 5 years.