Flybe when financially stressed in 2013 went for redundancies by fleet and by seat (also by base) with a matrix system where seniority was the dominant (but not overarching) factor. This was because they were told by lawyers that pure LIFO was “legally unsafe” (to use their words). I would suggest that the more important point for them was that this also allowed them to minimise their retraining bill. I have absolutely no doubt that this is how any European airline with multiple fleets and bases is going to play it and why, as a Gatwick pilot at BA, I’m absolutely crapping it right now.