Hyderabad, Sep 2 - The Bell 430 helicopter that went missing Wednesday with Andhra Pradesh Chief Minister Y.S. Rajasekhara Reddy on board had a valid airworthiness certificate, the state government maintained.

Chief Secretary P. Ramakant Reddy told reporters that the aircraft had been issued a certificate of airworthiness by the Directorate General of Civil Aviation (DGCA) on Dec 6, 2008, and it was valid up to Dec 5, 2010.

He said the helicopter was being flown by two experienced pilots - Group captain S.K. Bhatia and captain M.S. Reddy.

The others on board are the chief minister's special secretary B. Subrahmanyam and chief security officer A.S.C. Wesley.

The official said the helicopter was equipped with Emergency Located Transmitter (ELT), capable of automatic transmission on a frequency of 121.5 and 243 mega hertz which would have activated in a crash landing or in case of any unforeseen eventuality.

However, Dornier 228 aircraft which took off from the air base, air command, Yelahanka near Bangalore and is capable of picking up ELT frequency signals, did not pick up such signals despite flying over the area where the helicopter went missing.