Day 2 of the MH17 court hearings just started. The prosecution now is addressing the radar data analyzed by JIT. A theoretical description of primary vs secondary radar data is underway 
The prosecutor explains the various RCS (Radar cross-section) factors for different flying objects - the point is that a BUK missile is nearly infinitely much less likely to be captured on primary radar data than an aircraft.
Plus, in simplified terms, the settings of a radar installation define what degree of granularity (what threshold of RCS) is even recorded; "noise" and "clutter" from small objects is usually discarded
JIT requested Ukraine, Russia and NATO "AWACS" radar data. AWACS did not produce any relevant data. Ukraine could not provide primary data from the only in-range radar base due to "scheduled maintenance". JIT investigated such claims thoroughly.
After engaging international military and civilian experts and seizing and inspecting work logs, JIT validated that the radar station in Chuguev indeed had pre-scheduled maintenance on July 17. Other stationary radar bases within reach of MH17 were under Donbass militants control
Shortly after the downing, Russia's MoD showed radar data that showed a fighter jet in the vicinity of MH17. JIT requested Russia to hand over raw primary data from civilian and military radar bases. Russia handed over a video of combined primary and secondary radar data.
This video also suggested that a fighter jet had flown near MH17. When asked again for the raw radar data, in 2016 Russia said it had found the raw data, and it had discovered that what they thought was a fighter jet, was in fact pieces of wreckage.
(An anonymous source emailed JIT a screenshot of the Russian radar app showing the existence of raw data)
(due to a doctor's appointment will have to pause my love tweets, will try to catch up in an hour)
