EDITING POINTS

[nem]

It seems to me that declaring an emergency involves not just communication btwn the pilot and ATC but it also involves the mobilization
of emergency services and a whole host of other contingencies. Therefore, it's a ridiculous notion to declare an emergency 50 ft above
the runway as no one would be able to even react to your mayday anyhow.

Is it? (Yeah, I changed my mind on this again. )
If you get shot at shortly before landing, you just hear something go boom. You don't know what exactly happened, you don't know what might happen
after touchdown, you just know something is wrong. In an regular airliner like the A300 there are two people in the cockpit. One is preoccupied with
bringing the bird down, and rightly so. Granted. But the other would (I hope) get on the mike right there and then and tell the tower about the
situation, because IF something bad happens after touchdown the seconds (or minutes) between emergency services mobilized right after the bullets hit
or mobilized at a later time can make the difference in regard to the pax' health and well-being.

So I'd still say that it wouldn't be all that unrealistic to just hit Ctrl+Shift+M when you hear something go boom, regardless if in the final stages
of landing or not.