Although I find this theory of a fighter shadowing MH17 not very likely either, I do think that a dive isn't necessary to dissapear mostly unseen. Actually I think that would be a bad move. The populations of multiple villages would have known there was a jet. As soon as the launch of the BUK was detected, I think it's a much better plan for a jet to remain at the high altitude and dissapear in a direction taking advantage of layers of cirrus or haze. Who sees a small fighter jet at 10km? Perhaps it didn't care about being a second target because it knew it could avoid it anyway.
Again, this would only work visually and not too good. And not at all on radar.
And also, remember the big caveeat of the plan: It would be a suicide mission. The explosion radius of the Buk should be about as large or larger as the size of the radar cell for hitting a target. The fighter would be caught
There was speak about the BUK being an incomplete system without a separate radar module verhicle, therefore limiting it's capability. I don't know how these systems look from the inside and how advanced they are. But they need to be operated by these separatists. And I know what they look like.
Thats what it should look like. Nothing too unexpected there at first glance.
You can make a few assumptions there. First of all, the general layout of the radar systems is pretty constant since the 1950s. Technology maybe advances but the core functions remained the same.
It lacks a secondary radar - that is usually installed in the battery fire control vessel. So, that could explain why even a skilled operator could not know that he fires at a civilian target, he does not have transponder data. Also, it uses mechanical radar, so the radar information isn't as accurate as modern systems can. Since it is a TELAR, it also does not need target identification systems. It could sure tell an airliner from a small fighter by the comparing the strength of the return impulse on a mechanic indicator.
It has no classic PPI screen like ATC radar uses. It lacks the radar for those. Instead it likely is an B-scope. Other russian radar systems before the Buk already used those as primary display. This means: It shows the small sector that the fire control radar can scan and maybe rotates the view with the rotation of the launcher.
The smaller scope on the right should be an E-scope, providing the altitude data.
Finding a aircraft at a long distance that way is rather cumbersome, since the fire control radar only sees a very small sector of the sky. Without spotters telling you coarse direction and distance, you could be sending radar signals to half the NATO without seeing anything for a day.
If it had been visual spotters on the ground providing the data, they knew it was an airliner. If they had an external search radar (not integrated to the Buk system), they should at least have had the transponder data.
It is possible, that the Buk operator wanted to aim at a military target at a similar direction of the airliner and simply found the airliner as bigger target first. Remember, its a fire control radar, that only scans a very small sector of the sky in front of it. It could track the airliner without even knowing that the correct target is just a few degrees outside its radar display.
Still, it would be a criminal case of negligence, if the operator did not check his tracking data to the reported sighting of the military aircraft before firing. Especially he should have been aware that he is aiming at a much larger target than as he was expecting.
It would then also not be the guilt of the Ukrainian military, since they had been far away from the airliner and could only have prevented it by not flying at all.
My thoughts are that the settings of the incomplete BUK were left on it's defaults, in which it targets the most obvious target. MH17 was circumnavigating a bad weather area. It's weather radar in the nose would have presented an ernormous obvious target to the BUK outshining any other possible target.
Not at all - the large engines are usually the best radar reflectors. Civilian aircraft are huge radar reflectors.
Still, you could assume that having civilian traffic in the area as well allowed for hiding military aircraft among it. Sure one good reason for not closing the airspace. But then, since the Russians also read the NOTAMs, it should have been clear that firing at any vessel above 32000 ft means possibly firing at a civilian aircraft and should have been part of their rules of engagement.
And if I remember correctly - there was no bad weather in the region that day. The first pictures of the crash showed rather calm weather.