A lot of the "Risks" that people talk about have to be an individual decision. My son played both Football and Soccer in High School. Lettered and started for all 4 years in both sports. Soccer here is in the spring, because there's not enough kids normally in the state to play both football and field a team for soccer. Anyway; my son received his appointment the 1st week on November 2007. The exact same day his team won the state championship 5A football game. (first time in 34 years for his school). I knew he received his appointment prior to the football game that day, but didn't tell him until after the game. Didn't want to distract him. A couple of days later, the coaches from the academy football team called to also recruit him for the team. Needless to say, it was the greatest week of his life. But then he had to decide what to do with soccer and the rest of his year. Being football was over with for the season; and they wanted him to play on the air force team; and he already received his appointment; he chose to not take the risk by playing soccer that spring. (Believe it or not, injuries are as common in soccer as in football).
So, if pole vaulting is something you think you want to continue with at the academy, and possibly make the track and field team, then continue with the sport. If it's not something you think will be of much of your time at the academy or wherever you choose to go to school, then skip it and find other activities.
The bottom line is; the academy should not be your goal. The academy is a means to reaching your goal. Depending on what your goals are, you need to decide at what level of risk you are going to take. Make sure however that you still enjoy your life and the time you have left in high school. You'll never get this time back again. Best of luck. Later... mike...