There are several opportunities to take graduate studies as an aircrew officer. As dapaterson has said, there are post-grad opportunities offered each year that are usually based on you being posted to a certain job requiring the post-grad training you will receive if you are the one selected for the program. There are also opportunities to do grad studies on your own time (part time), and depending on where you are posted you may be allotted some work time to work on it. There is also an ROTP program where you can do PG immediately following completion of you bachelor's degree. I did this program, and it has certain advantages and disadvantages. I was able to do the studies in whatever I wanted (I chose physics) however I fell 2 years behind my peers in career progression. I've made up some of that time because my posting after receiving my wings had almost no wait time to get qualified, whereas some are looking at a 1 yr+ wait now.