A passenger plane flying from Moscow to Yekaterinburg is about to make an emergency landing in Kazan, a source in the aviation services told TASS on Tuesday.

"A passenger Airbus en route to Yekaterinburg to Moscow is making an emergency landing in Kazan," he said.

The plane sent a distress signal while flying over the Mari El republic some one hour after the takeoff and changed its course toward Kazan.