Originally Posted by selfin
FASID CNS/4A states both Banda Aceh and Lhokseumawe/Malikussaleh's PSR ranges are 90 NM. Apparently 60 NM might be closer to the truth.
The 90nm figure is obviously a politically motivated figure. 90 nm is about half the width of the Malacca Strait, so by stating 90nm the Indonesians are stating that they can only see over their own territorial water and have no capability over Malaysian territory. The fact is that for a primary radar the range limit will be about equal to the horizon. Factoring in a target altitude and the radar antenna elevation this will work out to something like 200 miles, probably a little more in practice. (The limitation of a radar's range will not be transmit power or receiver sensitivity, as even late 20th century technology has provided ample capability there.) It is possible that the Indonesian radar operators were blinded from seeing into Malaysian territory when looking to the east, but to the north they would have had a full 200 mile view, at least the military people would have had full range capability, if not the ATC too.
Originally Posted by selfin
MH370 was below Butterworth's RADAR horizon for a significant period enroute VAMPI.
VAMPI is a little over 200 mi from Butterworth so if the "significant period' part of that statement is true, MH370 would have been flying quite low in order to get below radar coverage. This is certainly possible.
Originally Posted by hamster3null
if last known radar contact is near NILAM and MH370 wasn't visible to Indonesian radars at that point, it's pretty straightforward to get from NILAM to 20.8S 104.1E in less than 2000 NM without getting any closer. If radar slide is false though, MAPSO-IGREX-TOPIN-IKASA-Ocean Shield is 2213 NM (370 kts) while giving a wide berth to Indonesian airspace.
I am projecting the necessity of a wider berth than you are, along with an assumption of lower altitude for a significant part of the flight, so that does make the fuel expenditure/ground speed to the northern parts of the search area a better fit.
The unknown here is what the Indonesian radar capabilities actually are, or what they were perceived to be at any rate, they have a 10,000 ft mountain about 30 miles south of Malikussaleh and it would seem logical for them to have placed their military radar antenna somewhere on that height.