The employees' insurance and benefits are locked in if they retire, but could be lost if they stay and strike.
George Monzo is 61 and has worked for Northwest for 41 years.
His last day of work is today. Monzo says he's too young to retire, but says he's afraid to gamble with his benefits.
The Aircraft Mechanics Fraternal Association says nearly a quarter of its membership of 82 retired this month. A dozen others bailed out last month.