Yes, Lydia is quite right !
That is what makes this one unusual. A 737, not a battered old Ilyushin or a Tupolev, the plane of the most sinister
of all the plane incidents, the Polish one mentioned by joasia.
That latter is still unsolved, by the way. Hopefully definitive information will be uncovered to permit
a conclusion being drawn. Otherwise it has been pushed away from the world's awareness after the
sad funeral of the leaders who perished in that flight.
Many theories have been advanced. Let's hope the truth arises from each incident !
Back to Boeing aircraft, they have always been TOPS [until perhaps recently when new model-airliners have
not proven as reliable as past ones].
The 707 was a veritable workhorse, handed down regularly after a good workout in the service of maybe 15- 20 airlines!
The 737 was a short - range aircraft never known for crashes.
[This is just off the top of my head, without researching.]
One cannot imagine that "equipment failure" would generate a sensational dive like that shown in the video.
Usually, a problem of landing gear not working would be resolved by a belly landing. Unsafe, but not a drastic plunge
into the earth as pictured there in the Tatarstan Airlines video. The plane was landing at its home base, too,
so it could hardly have been unfamiliar territory.
Maybe there should have been prayers read over the loudspeaker made to the Kazan Mother of God prior to takeoff and before landing !
It would be a good idea if ALL airlines flying in Orthodox airspace, so to speak would institute this practice !