A Russian MiG-29 fighter jet crashed into the Mediterranean Sea as it attempted to land on the Admiral Kuznetsov aircraft carrier, the defence ministry in Moscow said.
The pilot ejected safely from the plane, the ministry said.
The Admiral Kuznetsov is one of a group of ships which was recently deployed to the coast of Syria, where Russia is providing military support for the government in its war against rebel groups.
The ministry said the plane crashed because of a "technical malfunction" during a training flight a few kilometres from the ship. The pilot was picked up by a rescue team, it said.
US defence officials told Fox News that the plane was one of a group of three which was en route to a mission in Syria and turned back when it encountered technical problems.
The carrier was part of a flotilla including a nuclear-powered battle cruiser, two anti-submarine warships and four support vessels which sailed down the English Channel en route to Syria in October.
Nato has expressed concern that planes on the vessel could be used to target civilians.
Russia is reportedly poised to launch a new wave of bombing missions in Syria from its aircraft carrier and air bases in southern Russia.