Russian flag-carrier Aeroflot has been forced to postpone introduction of Boeing 777-300ER services, after a hold-up in the local certification process.
The aircraft, which was formally delivered to the carrier in Seattle on 30 January, had been due to operate flights from Moscow to Bangkok on 1 February.
But Aeroflot says the Interstate Aviation Committee, which oversees certification, has not issued the necessary type certificate for the twinjet.
Russian authorities certificated the 777-200 in March 1998 and this approval also covers the 777-300 which is operated by Moscow-based Transaero.
The airline says it will be drafting Boeing 767 and Airbus A330 to operate the Bangkok services instead, and reassigning passengers to different cabins.
Aeroflot says it has complied with all necessary legal procedures to introduce the new aircraft, and insists it will "take action to recover damages".
The Interstate Aviation Committee and federal air transport authority Rosaviatsia have yet to clarify the nature of the hold-up.
Aeroflot placed orders for 16 777-300ERs, which are all powered by General Electric GE90 engines, in the first half of 2011.