^i'd add on to that:
-AC's move from a highly regulated environment to one with less regulation.
-the effects of the baby boom.
-recent stock upheavals (late 1990s, 2008) and ongoing low interest rates x ~ 10 yrs
- a probable policy on all sides to get smooth labour relations now for a defined-benefit pension to be paid later. To be fair, it seems this was common among other companies and the public sector in the 1960, 70s.
also remember that these are "defined benefit" pensions where the amount retriees gets paid is predetermined by agreements made long ago, regardless of the current economc condiion or the return of the pension's investments. Compare this to say, an RRSP, a
defined contruibution plan.