To follow on from Pax Vobiscum's knowledgeable posting:
The £1.8bn figure was probably from a BA press office deliberate 'leak' which the papers appear to have swallowed wholesale.
The value of the assets in the fund has just been published at £5846m. The liabilities are of course not known, but working forward from earlier figures, it is quite possible that the fund is now actually in surplus.
BA are masterminding a gigantic con trick on their long-serving employees in order to feather the nests of a few management fly-by-nights.