DGCA said the Mumbai-based GoAir is currently operating with four aircraft, against the requirement of five aircraft to retain a licence for scheduled operations.

"We will seek a justification from GoAir for operating only four aircraft," said Director General of Civil Aviation Kanu Gohain.

According to DGCA guidelines, the scheduled operator will have to operate a fleet of minimum five aeroplanes either by outright purchase or through leasing.

DGCA guidelines allow a commercial airline to start operations with one plane but the number needs to go up to five for retaining the scheduled operating licence.

When contacted, GoAir Managing Director Jeh Wadia said, "We have not violated any civil aviation guidelines. We had seven aircraft during our first year of operations."

Around four months ago, GoAir had returned two aircraft to lessors as a part of its "dynamic fleet strategy" that involved inducting more aircraft in the peak season and letting go in the lean season.

Wadia had earlier said, "GoAir is currently working on its flexible fleet management plan to achieve sustainable growth. This October, we will receive the first of our brand-new 20 aircraft. We plan to expand our current fleet of 5 aircraft conservatively to 18 by March 2009 and will subsequently adopt an aggressive growth pattern, going up to 34 aircraft by March 2011."

GoAir took off on November 4, 2005, with scheduled services from Mumbai.