Last night's viewing - Bluestone 42, BBC3; The Crash, BBC3

I think Bluestone 42, BBC3's new comedy about a bomb-disposal team in Afghanistan, may be unique. Of course, there have been other sitcoms that tried to see the funny side of a bloody war before now. M*A*S*H did it brilliantly, as did Blackadder Goes Forth. But neither of those series went out while the war in question was still underway.

True, M*A*S*H might have been a Vietnam series by default, but it took care to locate itself in hostilities that had ceased. You might argue that, strictly speaking, this is also the case with Bluestone 42, since British combat operations in Afghanistan have now ended. But there are troops still on the ground there and the ground is not safe. For every reason, scheduling being the least of them, one hopes, the BBC must be praying that it won't have to suddenly pull an episode because its transmission doesn't sit well with the news bulletin that preceded it.

Leaving aside the question of whether it's unique, there's the more important matter of whether it's funny. And the answer is: only intermittently, the stuttering nature of the comedy coming about because Richard Hurst and James Cary haven't quite decided whether to write a sitcom (comic exaggeration allowed and encouraged) or a comedy-drama (comic exaggeration reined in by realism). The length is sitcom, but the style often isn't, with off-duty sequences that obviously owe a lot to their research with serving soldiers. And the performances sit uneasily somewhere between the two, the awkwardness most pointed in Oliver Chris's Captain, who flutters between straight acting and caricature in a disconcerting way.

Hurst and Cary make it clear almost immediately that they're not going to dodge the bullet of combat deaths by having a visiting American blowhard fail to dodge a bullet while out on patrol. It's a kind of declaration of intent – though it's a compromised one, the character being so obnoxious that he's clearly been written to be killable without causing any distress to the audience. They also serve notice that they're not going to tone down the saltiness of frontline life, with two Scottish squaddies providing the funniest moments. Trying to impress the new female padre with his sensitivity, the Captain agrees that it might be helpful if she counsels those who've just seen the American killed: "The young lads in particular... it can hit them very hard," he says gravely. At which point, the lads in question race past squabbling: "I just wannae borrow yer wank mag!"

That kind of gag – drawing on the bawdiness and blunt wit of barrack-room talk – works more effectively than more elaborately plotted comedy of embarrassment that arises out of the Captain's attempts to woo the padre. But there are promising elements here, including the presence of Tony Gardner as a cynical base commander and the mere existence of the thing itself. "Brave" might be overbaked to describe Bluestone 42. If it does eventually go off in the face of those who commissioned, it they're not going to lose a lot. But it's not cowardly either, and that's worth applauding.

The Crash, a drama about the aftermath of a fatal traffic accident, is like an extended version of one of those road-safety adverts aimed at teenagers. You'll have seen the kind of thing: all giddy warmth one moment and then a crunching transition to tragedy. The first episode of Terry Cafolla's two-parter concerned itself almost exclusively with prelude, a teen photo-romance full of budding ambitions and evolving relationships ready to be cut short. As I was watching, I thought it a little oversweet in the writing, with a faintly synthetic sense of youthful exuberance. But something must have worked because the crash that came at the end was genuinely upsetting. The second episode should reveal whether it amounts to more than an unusually detailed public-information film.