QUOTE (onesliceshort @ Feb 1 2011, 03:33 PM)
Nice work Tume.
The strangest aspect for me is that the area below the Annex is well below the ASL of the "missing blip" area.
Can I read about the limitations of the radar anywhere?
I think there are some informations about radars sparsely scattered arround internet. I'm using the bit I've learnt in the school (electronics college).
But basically the limitation relevant here for the ARSR radars is the direct visibility from the radar to the point where the object in the air is or is supposed to be - to be exact.
Usually - with the 3D radars - the visibility statistics diagram looks like this:
but PLA is ARSR-3 which hasn't the 3D cappability for Search type messages, so only if the transponder is on, the radar records the MC altitude. For PLA you dont see any Search type blips (light green) in the diagram:
Basically the limitation is if there is a hill inbetween, the ground based radars can't see behind. That's why I think the two last 84Rades blips for "AA77" shouldn't be from the "AA77" plane, because 1. it doesn't correspond with the time compared to NTSB animation (bearing in mind the alleged NEADS time lag 25.3 sec) and 2. the plane would need to be at least the ~96 meters AGL, otherwise I'm afraid the PLA couldn't see it anyway.
But for now I'm still digging in it, trying to figure what is probable. There are very weird things in the 84Rades data in respect to "AA77" - for example the sudden reappearance of the plane at 38°25'17.01"N 80°46'56.57"W
(the image is elplot statistics for PLA showing how far the radar sees - or in this case - another weird thing - is in visibility cut at 200 nmi - even yet the plane "reappears" not sooner than at range 147,5 nmi)
I was looking also at the height profile and it doesn't seem there is an obstacle in the way which would be why the plane eventually would not be seen by PLA earlier - if at the altitudes shown in the NTSB animation (>20000ft). There just isn't any 20000+ft mountain. There still are many puzzles in this which is why I'm not very convinced about the 84Rades integrity...