Had to take medical retirement a few years back.
Moved into Flight Ops Quality, (Qualified as an auditor) then Flight Safety. Worked on quite a few different projects including SMS.
Been with present employer 4 years. If you had other skills before you went flying, might be worth falling back on those. If you have to take a desk job (for whatever reason) and you have had a predominantly aviation working life, then stick close to that. It is the subject you know best, and you will have transferable skills into management. Before going it alone, it is probably best to get some company experience. If you know anybody in any aviation safety dept, in any company, then go and have a chat with them, see what the job entails. I am sure they will give you an idea. Flight safety is partly what you bring to the position, partly how you are connected (or who you could connect to) and do you have an empathy for people.(Diplomatic skills needed)
Like many jobs it has plenty of responsibillity and a degree of authority. It will appeal to those with a problem solving and creative mind. It can be tedious in places, but it will be very rewarding.
Remember that "safety" is not something you have.........its what you do
Books on my bookshelf......Anything by Sidney Dekker, and right now, "The ETTO Principle" by Prof Hollnagel - fascinating stuff.
BS