Get ready as NDA Application Forms are coming in first week of January. Get link http://www.upsc-2017.in/nda-exam-date/

In order to join Indian Air Force after 12th you have to qualify for NDA exam. It is conducted by UPSC. 

In order to eligible for NDA exam you must be between 16.5 and 19.5 years of age. 

Candidates who will qualify the written test of NDA 2017 will be called by Services Selection Board for Intelligence and Personality Test

To know in detail you can refer below link

NDA 

Good Luck!!