The Russian state seems to be dogged by bad luck. The last week was particularly bad. Firstly the Russian ambassador to Turkey was killed and now a TU-154 with 92 passengers has crashed. The plane took off from Sochi   lost radio contact and by all accounts crashed into the Black Sea The plane carried the famed Russian army band to entertain the troops in Syria, where the Russians have a large presence. The plane had a crew of 8 and was piloted by an experienced pilot who had logged over 3000 flying hours. The crash of the plane is a mystery and perhaps the truth will only be known once the black box is retrieved, which itself is a herculean task considering the plane crashed into the Black Sea.

The TU-154

The TU-154 is a 3 engine plane and is mass produced. It is also Russia's most popular model and is supposed to have a good safety record, but it has had some terrible crashes and hundreds have been killed. The plane looks similar to the American Boeing 727.The plane took off in good weather and it was classified as airworthy. Hence the crash immediately after it lost contact with ATC is an enigma. 
Mystery
Earlier a Russian airliner was taken down by the ISIS in the Sinai. There have been quite a few crashes in Russia and that does not auger well. Maybe the security apparatus needs to be revamped as this TU_154 may also have been targeted by the enemies of Russia.
A search is on and the Russians better satisfy themselves as quicky as possible as to the reason for the crash