Special leave might be an option as well. You would be surprised how many people would like to have a year or two off and head for the hills or devote more time to the golf game, outside business interests, go traveling with the family and kids, fly for another carrier on heavier metal etc. So long as seniority is protected and provisions put in place for pension payments and they get first back in when rehiring starts again it can be a win win for all involved and might save the more junior people who are after all relatively cheap to employ.