To become a pilot in the Indian defense service, specifically in the Indian Air Force (IAF), you need to follow a structured process and meet certain eligibility criteria. Here's a general overview of the steps involved:

1. Educational Qualifications: You should have completed your 10+2 education with Physics and Mathematics as compulsory subjects. Some positions may require a specific minimum percentage in these subjects.

2. National Defense Academy (NDA) Exam: One of the pathways to becoming a pilot in the Indian Air Force is through the National Defense Academy. You can apply for the NDA entrance examination, which is conducted by the Union Public Service Commission (UPSC). The exam comprises a written test followed by a selection process that includes a physical fitness test, intelligence and personality tests, and an interview.

3. Air Force Common Admission Test (AFCAT): Another way to join the Indian Air Force as a pilot is by appearing for the AFCAT, which is conducted by the Indian Air Force twice a year. The AFCAT exam assesses your knowledge in subjects like General Awareness, Verbal Ability, Numerical Ability, and Reasoning.

4. Pilot Aptitude Battery Test (PABT): If you qualify for the written exams (NDA or AFCAT), you would need to undergo the PABT, which evaluates your aptitude for flying. It includes tests that assess your spatial orientation, coordination, and multitasking abilities.

5. Medical Examination: Clearing a rigorous medical examination is a crucial step in the selection process. You must meet the specified medical standards, including visual acuity, physical fitness, and overall health, as per the guidelines set by the Indian Air Force.

6. Selection and Training: If you successfully pass the written exams, PABT, and medical examination, you will undergo further selection rounds, including a personal interview and group discussion. Once selected, you will undergo rigorous training at the Air Force Academy, where you will receive comprehensive training in flying, combat techniques, aviation systems, and military operations.

It's important to note that the exact selection process and requirements may be subject to change, and it's recommended to refer to the official websites of the Indian Air Force and the respective examination bodies for the most up-to-date information. Additionally, seeking guidance from career counselors or individuals already serving in the Indian Air Force can provide valuable insights and advice specific to your situation.