Service in airports authority of India is countable or not for old pension scheme

I joined Deshbandhu Gupta College ( University of Delhi - Autonomous Body) in 1999. Where old Pension Scheme was applicable. I applied through proper channel for Staff Selection Commission, Graduate Level Examination and Airports Authority of India (Statutory body/ Public Sector Unit under Ministry of Civil Aviation) in 2004. I got selection in Airports Authority of India in 2006 and joined on 06.09.2006 as Junior Assistant in Pay scale of Rs. 5500-9000/-(in IDA scale) on lien. In 2008, I requested to the college to accept my resignation from 06.09.2006(F/N) and the resignation was accepted by the College from 28.10.2008(F/N). Final result of SSC(Graduate Level) 2005 was declared in December 2007 and I was offered for the Post of Assistant in Ministry of External Affairs. Due to my personal problems, I applied for extension to join as Assistant In MEA. and the same was accepted by the Ministry of External Affairs. I joined Ministry of External Affairs on 29.10.2008(F/N) after acceptance of my resignation fby AAI. Please suggest whether my continuous past service is applicable for Old Pension Scheme as I was in Old Pension Scheme in Deshbandhu College.