DSB used the ‘at the glass’ recording of the primary radar of Rostov (Russia) to determine that no other aircraft besides three civil airliners were in the vicinity of MH17. At the glass means that a video recording was made of the radarscreen as seen by the air traffic controller. The other method of saving radar data is raw recording. This method of recording saves all unfiltered radar returns, including returns from objects to small to be of interest for air traffic control purposes.
However, DSB never states in the final report that radar has a horizon. Aircraft flying below the horizon on a radar cannot be detected. The horizon of the radar depends on characteristics like height of the radar antenna, power of the signal and distance from radar antenna to the target.
For aircraft to be detected by Rostov radar the aircraft must be flying higher than around 2 km.
At page 128 of the final report DSB states : ‘in addition, for an air to air missile to have caused the damage found another aircraft would have to been recorded by at least primary radar’.
There are two objections to this DSB statement:
- DSB does not mention the horizon of Rostov radar anywhere in the report. The report suggests: not on radar so no military jet near MH17.
- Many air to air missiles can hit a target when the fighter aircraft is flying many km below the target. For example the R-27 has a maximum allowed vertical separation of +/-10 km
While it is very unlikely the R-27 was the missile that shot down MH17, DSB should have been clear about the radar horizon of Rostov and capabilities of the missile.