Celebrim
Legend
So how would everyone else handle this?
It's a normal combat situation.
There is an obvious reason why. Suppose that the orcs now adopt the same tactics. How do your players feel about orc archers achieving die no save hits on the PC when they are not fighting back?
I play a homebrew version of 3e and a sufficiently high level Hunter could pull of this sort of shot reliably, killing the orc with near certainty. It would be well within the rules for a high level hunter to make a single arrow shot that did 4d8+10 damage, with a 10% chance of a critical hit for about 10d8+30 damage - a total all but guaranteed to additionally provoke at least one and possibly two catastrophic damage checks with, because this is a Hunter, a very high DC to save even in the unlikely event this was a rather high hit point orc. A multi-classed Hunter/Rogue with suitable feat selection could also pull this off. And that's really not getting into all the possibilities available with magical weapons and buffing.
Despite the lack of realism in a hit point system, there is out of game justification for it being difficult to make this shot lethal. There is only a pretty small portion of the orcs body where you could place an arrow and have it kill the orc more or less instantly, and you are trying to hit that target from over 60 yards away. Further, it's likely that the orc is armored to at least some extent and in particular if he has armored any part of his body, it's the parts which are so vulnerable that a hit there means death. So the arrow must hit with force and hit the yet smaller portion of the body insufficiently defended. Realistically, for a kill shot with an arrow, you are talking about something like putting an arrow through the orcs eye at 60 yards.
Any bow hunter will tell you that dropping a deer with an arrow at 60 yards is a very difficult shot. You need to make a shot that pretty much splits the heart. Anything less, like puncturing one or both lungs or hitting a major blood vessel, only means that the deer will bolt and then bleed to death over the next few minutes. Anything less than that, and you are looking at a potentially lengthy period tracking your kill down to wherever it ran to die. At 60 yards, most serious hunters won't even risk a shot, because they've encountered far to many deer with old arrows sticking out of them because some other hunter made a bad shot and just stuck the deer in a non-lethal manner.