Recently off the phone to an ex-RAF mate who was a UK Air Defence Radar guy .. it seems I may be wrong in my comments above ....
Apparently, due to the high number of aircraft that an Air Defence radar has to track .. ie every single plane in the sky in the region, a methodology has been developed whereby the radar signature can be annotated with one of 3 designations .. "F" - known friendly - "H" - known hostile - "U" - unclassified. An aircraft with an "F" designation will not be tracked with any high degree of interest .. the Air Defence job is the "H's" and "U's"
So, how does an aircraft get an "F" designation ... basically either from its flight plan, or later attached by an operator. MH370 departed from Malaysian airspace on time, on a pre-planned, approved flight planned route... it would therefore be marked as "F".
Unless, and until, an operator changes that designation it will remain, there is no automatic change. The "turn back" would not be questioned as, from a Military Air Defence viewpoint, it is still friendly, and the re-route could be for any, Civil, Air Traffic reason. ....
That's my understanding of what he told me, and may not be accurate or how the Malaysians operate ... but it does make some things more understandable... to me at least ..
