Hello Poonam,

Recruitment in AAI will be based on GATE 2018, so it you stood in top 100 then you will be called for document verification. Selection process is quoted below as per official notification --

"Screening and eligibility will be based on the details provided by the candidate. Candidates shortlisted on the basis of GATE Normalized Marks will be called directly for document verification which will be held at Corporate Headquarters at New Delhi."

You can check your best possible option by using career360 prediction tool.

https://engineering.careers360.com/gate-college-predictor?icn=gate-clgpd&ici=QnA_Answer