If you want to do Aeronautical Engineering you should be passed with 10+2 from any recognized board.You Should be totally from science field or stream,With physics,Chemistry and Mathematics compulsory Subjects.You can Choses optional subjects Informatics Practice (I.P) as an optional instead of Biology.It will be Beneficial for you.

Beside this after 12th best colleges and Institute in Kerala is as followed for Aeronautical Engineering:

Indian Institute of Space Science and Technology.
Thiruvananthpuram, Kerala.

Jawaharlal College of Engineering and Technology.
Palakkad, Kerala.

Rajadhani Institute of Engineering and Technology.
Trivandrum, Kerala.

Regional Institute of Engineering.
Trivandrum, Kerala.

Sha-Shib Aviation Academy, Cochin.
Cochin, Kerala.

Good Luck!!!