Sorry guys but your radar horizon figures are all wrong.
PN, I used the equation ((maximum distance radar can see aircraft) = (distance to horizon from radar site) + (distance to horizon from aircraft)). This supposes no intervening terrain, and the track was in fact entirely or almost entirely over water.
These distances were calculated using: ((distance to horizon in nm) = (square root of height of aircraft or radar antenna in ft) X 1.23).
For the radar antenna, which is at 2700 ft, the distance to the horizon is 64 nm.
The reported distance from the radar site at which MH370 went off the scope is 200 nm. If we subtract 64 nm from that, we see that
if the disappearance was because it flew past the maximum distance the radar could see it at, the distance to MH370's horizon had to be (200-64 = 136 nm). Dividing that by 1.23 and squaring the result gives an altitude of 12225 ft. Obviously, the precision of the calculation is swamped by the imprecision of the data.
Aircraft altitudes for some other loss of contact ranges:
230 nm > 18214 ft
240 nm > 20499 ft
250 nm > 22867 ft
As I said, these numbers don't agree with the observed altitude of MH370, so I don't think going over the radar horizon was the reason for its going off radar. It is just barely conceivable that Pulau Perak could have masked the return, but, again, that is terrain masking and not flying over the horizon.