Russian air controllers have lost contact with an airplane carrying 44, the Interfax news agency has reported.
It quoted the Emergencies Ministry as saying contact with a Tu-154 flying from Moscow to the Black Sea resort of Sochi was lost at 1900 GMT, when it was expected to be 140 kilometres from the southern city of Rostov-on-Don.
Earlier, the Itar-Tass news agency said that at about the same time another Russian airliner with 34 passengers and eight crew on board crashed south of Moscow.
The Tu-134 aircraft was en route to Russia's southern city of Volgograd when it disappeared off radar screens, emergency officials said.
Local policemen later found the crashed airplane near the village of Buchalki in Tula region, officials said, adding that local rescue services had already rushed to the site.
The fate of passengers and crew was unclear.
-- AFP/Reuters
Do you know what time 1900 GMT is in Moscow local time?