I think he means the total military obligation active/reserve that is on your contract. I thought it was still 8 years. In any case, there is no min obligation on active duty to satisfy the terms of the basic military obligation. Of course, your program requirements are in play here. An intel guy owes 4 years active, for instance, and the balance reserve which can be IRR or drilling. IRR means you do nothing, no drills, they just keep track of you and you can be recalled. That is still very unlikely for Navy guys, even these days. If a guy does not complete his training program for any reason and the Navy says "thank you for your service don't let the door hit you in the a$$ on your way out", then you owe the balance in the reserves. Realistically, if an aviator goes through all his fight training, operational tour and first shore duty orders, or the payback for wings, he will likely be past the initial obligation.