@BATHIK
"then there was a huge drop to 563 or something"
Until the speed 893 or so the flight was normal.
Then the destruction happened between radar display frame refresh.
Missile explosion did it's damage in 0.01s, after that the broken front of the plane twisted to right and I assume the nose broke off in less than one second. For a small periode of time the plane was banana shaped, therefore it made the 20g turn to east/north and broke down more.
The turn took away big part of the kinetic energy of the plane and as it's speed decreases, also the slowing force from air friction become smaller, slowing slows down and the speed angle starts to be more towards ground and radar does not show that.
To me the radar jumping is caused by the plane body and nose separating from each other.