With a Monday-Friday job, one might expect to work 35-40 hours and be considered full time. With crew schedules being this on, this off, back to back, etc., it's a little harder to count...
Accepted, someone who strikes is probably not going to be full time that week, but the dispute started before strike action was taken and crew who were working full time claim they weren't making what BA says they make.
I wouldn't consider someone who takes time off work in a week (for whatever reason; sick, leave of absence, strike) to be designated a part time employee - they're full time, but with a circumstance that week...
However, as a starting point, if we assume that 40 hours is a 'normal' full time week for crew, then 40 x 52 x GBP3.00 = GBP6,240.00, of which a portion is intended to be spent on expenses. Adding that to the base of GBP12,192 gives only GBP18,432 p/a, plus discretionary bonuses. If crew work an average of more than 40 hours then that'll be higher, but of course a portion of that is still intended to be spent, not retained - crew do not get expenses on top of this. If it's less than 40, well that's even worse...
I wonder what an average full time crew member's hours actually are?