Putin landed at the same airport three days
earlier. The bulb replacement therefor cannot
be anything but deliberate murder.
Tu-154 is equipped with several devices to warn you of your altitude, though. Including TAWS.
http://www.uasc.com/products/taws.aspx
Even with a completely dark runway, the pilot should not have been so low.
The lightbulb theory really isn’t going to explain the crash, imo.