Guppiebugs
88kts GS was the final recorded value in the software log from a guy with a Radarbox Mode-S receiver who is fairly near EHAM, and has coverage of aircraft on the ground there so would be able to receive the Mode-S from where TC-JGE was before impact.
Naturally because the position, speed and height transmissions are not all sent at the same time you can't say the three things are coincident, but they will be within a second or so I would say.
I'm just trying to give people an idea of how far below Vs they were just before impact.