Using equity to meet current obligations sounds a lot like a Ponzi scheme:
> A Ponzi scheme ... is a form of fraud that lures investors and pays profits to earlier investors with funds from more recent investors.[2] The scheme leads victims to believe that profits are coming from product sales or other means, and they remain unaware that other investors are the source of funds.
https://en.wikipedia.org/wiki/Ponzi_scheme
Provided that the equity drain is limited in scope, a pension fund can continue to fight another year.
The more interesting (or scary) question is what happens when tapping into the equity becomes the norm? At what point does the fund manager level with pensioners and inform them that the fund is in fact insolvent?