A crew member of a UTair Boeing 757 flying from Bangkok to Novosibirsk in western Siberia died as the plane was flying over China, transportation prosecutors said Friday.

Sergei Golev, 44, sustained a heart attack in the cockpit and died despite all attempts at resuscitation, a local prosecutor’s office spokeswoman said, Uralinform.ru reported. Even a cardiologist found among the passengers failed to revive him.

The chief pilot attempted an emergency landing in the Chinese city of Chengdu, but abandoned it because Golev died before the jet touched down.

The incident took place on Tuesday, but was not reported before. The Investigative Committee opened a mandatory check, to be wrapped up next week.

Some media reported earlier that the Boeing was bound for Moscow and executed an emergency landing in Novosibirsk, and that Golev, though a pilot, was flying as a passenger.

But a spokeswoman for the regional transportation prosecutors told Komsomolskaya Pravda on Friday that the plane was flying to Novosibirsk and that Golev was a crew member – a reserve pilot, tasked, ironically, with replacing a crew member in case they fall ill.