Re. transponders: actually, most of the time these are turned off.

To our luck (not so much to the luck of Tunisia in general, though), there are enough people on the ground having enough time to watch…

Re. transponders: actually, most of the time these are turned off. Indeed, I can go as far as to say that they not only have their transponders turned off: they refuse to reply to any request for ID even if called to do so.

To our luck (not so much to the luck of Tunisia in general, though), there are enough people on the ground having enough time to watch what’s up in the skies around them.

Indeed, that’s precisely one of the problems: the latter can’t always clearly ID what’s flying above them - except describe some of the ‘stuff’ in question as ‘twin-engined biz-plane’, ‘four-engined transport-like’, or ‘UAV’.

Re. extremists and their capabilities: well, it seems the gang there is nowhere near as sophisticated as to know what’s flying above them (if they get to see anything at all).

Arguably… well, that’s one of reasons why writing and publishing articles like this one is a kind of ‘double-edged sword’.