The reason for Sunday’s aborted takeoff was not immediately clear. Russian news agencies quoted air show officials as saying only that the reason was “technical.”

The T-50 had been kept out of the public eye before its debut at the air show on Wednesday during a visit by Prime Minister Vladimir Putin.

The twin-engined jet is intended to match the US F-22 Raptor, which entered service in 2005.

The Russian fighter still lacks new engines and state-of-the art equipment, and its serial production is only expected to begin in 2015 at the most optimistic forecast.