so why ask in the first place
Well, one good reason for that - not squawking/military traffic. It might be there, it's not on the TCAS, it won't trigger any alert.
And if we're talking about TCAS already - it'd be nice if pilots would start to notice that it's not a radar and shouldn't be used for self-separation.
Another one is that if the guy's flying through military airspace, he might have been checked for that route +-1-2 nm and outside of that it's the big bad world of all the militarys got... I've had an AirBerlin once flying IN an active firing range, coordinated with mil (it was their screwup, they didn't know about the navy's firing range being activated right when the BER was in the middle), so they only said tell the pilot they're not shooting at them but they must stay exactly on route for their own safety. In that case I did tell the pilot about all this, but I wouldn't if it was just a "simple" crossing of a TRA or something.
Not talking about turning into a firing range...
Thanks for all the answers!
One more thing - strictly speaking it's a deviation from the clearance isn't it? In some countries I believe you get the fighters behind you much quicker than here for this... I wonder if they do it there too... I know that in the old days in Eastern Europe it worked like that - air defense was looking at the civil traffic all the time looking for the one that's not going on-route and in the moment they saw something that wasn't planned/coordinated they've launched the MiGs... And it wasn't just a friendly wave and then go home kind of interception, but forcing the guy to land...
bookworm:
I'm sure that pilots could make much better efforts to make it a sensible negotiation, but I do sometimes get the impression from this forum that controllers get into the mindset that mid-air collision is the greatest, or even the only, threat to aircraft safety. While that mindset is perfectly understandable, history tells us otherwise.
Could you just tell me on what range do you usually have your wx radar set? How often do you look at the picture displayed? Do you look out the window sometimes? I think unless you've been sleeping in the last 10 mins of flight you can see things well ahead and not only when you actually need the turn.