A simple principle in building a successful business "keep your customers" you are going nowhere if for every new customer you get you are loosing an existing one. This is also true of your employee's, the first principle should be to keep what you've got, in aviation this is even more critical because of lead times involved in getting experienced people to the line.
Look at the work force, the young, middle and old, the old may have the loudest bark but sadly no teeth, these people are not going any where fast, most have nice FS pension and will stay. The young well there bonded to start with. All these people are at the start of there careers building experience and hours. The North Sea is the place to do this and most will stay in the medium term. The week spot is the middle ground SFO’s and mp pension type Captains, keep these people happy and your on a winner. Forget giving any of these groups exclusive deals at the expense of the rest this will not achieve the desired effect “retention” and will only serve to alienate the other two groups.
Target the problem with a simple solution. Offer the work force a loyalty payment for signing an agreement to remain with the company for a five year period .10K on signing followed by an annual loyalty payment of 10% of the annual salary paid in arrears for every full years service.