P to T
Just a few questions and observations on about your predicament.
I take it that this backward move is not in any way associated with getting you into the LHS either now or in the near future?
Are the company actually getting rid of/reducing the number of the type you currently fly and want to stay on?
Are you the most junior on your type?
Did you sign a contract agreeing to this bond system, (possibly didn't even notice a second bond clause, just too happy to have a job)?
You don't have to take legal action if you don't want to but you CAN and SHOULD take your contract to a solicitor, pay their fee and get sound advice - if only for your peace of mind and to establish if your employer CAN actually make you redundant if you decline the new type. It doesn't sound as though it would comply with UK law if they did but your contract may take precedence, again, this is solicitor country and you should talk to one.
Best of luck - you may have to bite the bullet for a while and just increase your hours and experience.