Hi There,
As a female at 17yrs you will need to complete your 1.5mile run in 14mins 24secs. The trade of PTI has a specialist interview and during this they will assess your fitness. You will have to complete the 'bleep test' to your best effort and I also understand they ask you to complete as many situps and press ups in a 1 minute period. You undergo a swimming test which includes 60m breast, 60m Front and 60m freestyle. You will also need to retrieve a brick from 3m and tread water for 2mins with your hands out of the water. They assess your sport playing and coaching ability. This is an idea of what to expect, your AFCO are in a better position to advise you further. The specialist interview is conducted in the school of PT at RAF Cosford. You may be able to get information by doing a search on google, etc. Not sure if they assess a 3mile run however as an example, Gnrs are expected to run this in 24mins. I wish you every success for the future and remember, I'm 'Here to help'