The sentence in parenthesis is what doesn't actually fit with helicopter use, and I don't really know what all that after the comma means. :shrug: (it made sense when I typed it)
I have seen Blackhawk Down, and I did know that Apaches could be rendered combat ineffective by small arms fire. However, this is not Iraq, it's Unspecified-istan, and their military sucks big hairy donkey balls, by all measure. The Blackhawk Down scenario occurred because a multi-division size force of Somali militia with heavy anti-vehicle capability engaged two (numbers check here) companies of Rangers and Delta Force that had no real supporting armor and only helicopters for effective infil- and exfiltration. If anything, it is a wonderful example of why any kind of cavalry unit should never, EVER get bogged down by anything. Then again, CoD 4 does not use helicopters in a cavalry capacity, but strictly as a deployment option. Notice how you're only in the Chinook to get your whole squad and then some the hell out of there, not deploy just you chalk into combat.
You know, come to think of it, both times you land in that Chinook, all of your flanks are covered by three or four story buildings, except when you try to rescue the pilot, and in that case, the terrain "behind" you is open field with no hostiles. The ramp crew and several marines take up covering fire positions along the fuselage.