My bad for not being clear on that, HR Diva. UAL's contract (as HuggyU2's pointed out) allows UAL pilots to remain on mil leave for a total of 6 years. It even allows you to be on mil leave for 5 yrs, 9 mos and then not report back to UAL for another 3 months.
Due to AF reserve rules, I will have to return to UAL for approximately 10 months halfway through that 6 year stretch. AF Reserve only allows a member to serve on active duty for 1095 days on a 1440 day rolling calendar. This breaks out to three out of every four years.
I have a few motivations for remaining on mil leave. Most importantly, I enjoy my job ... it is outside of the flying arena in a joint staff position. Secondly, I currently have 18 1/2 active duty years toward retirement; I'd like to be able to get a retirement immediately after military retirement rather than wait until I turn 60. Third, UAL puts 15% of my base pay (what my base pay would be) into my 401k while I'm on military leave of absence.
For any airline pilot off of probation who is part time military, taking mil leave is a great deal. To be sure, I wouldn't want this big of a flying gap if I were still on probation.