Hello,
If you are aspiring to join Indian AirForce after your Engineering that too in aeronautical is a good option. you can apply for the AFCAT exam and choose Aeronauticals in your preference. You must be less than 24 years old. you must have 60% in your 12th in Physics, Maths for Flying, technical and you must have 60% and above in Graduation then only you can apply for AFCAT. For flying and technical there are some medical standards needed do see those requirements.