You need to pass the 10+2 exams from a designed state board after which you need to pass any entrance exams or any exams specially organized for that institute, also you need to focus on the eligibility criteria which they affix and which you will get admitted accordingly through the counseling procedures.

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After your 12th in Physics, Maths and Chemistry, you need to write entrance exams of the respective colleges and universities with that course. The link given below will assist you in your query 

https://www.sarvgyan.com/courses/engineering/aeronautical-engineering