Someone earlier on mentioned MH030, KL to IST. Out of curiosity, I tracked the MH030 flight of last Saturday on FR24, and now have a query.
At the time MH370 disappeared from FR24, MH030 was about 150km south of Penang,tracking NW. At around 18:01Z, when about 100km NE of Bandeh Aceh, it disappears from FR24. Letting the playback run, I saw that all flights disappear from FR24 at that point, unless they're a bit further north towards Phuket. I presume that FR24 don't have access to equipment in that area that can give them transponder data.
I'd assume that ATC and so on would have access to other sources and would still be able to 'see' those flights. I really can't believe that military radars would be unable to identify a plane at that point and thus see all flights as warning blips. Would they?