Facts:
aircraft involved: Tu-154M reg 101 (
http://russianplanes.net/REGINFO/3143)
maintenance status: not known yet
airfield: Смоленск-Северный (military, north of Smolensk, 2,500m rwy)
conditions: low visibility
other: three aboarted landings a fourth attempted landing underway
Possible causes:
low visibility combined with psychological stress for the crew caused by VIP pax
The real cause will be finally found by the investigators.