yes.. this is possible.. usually it only happens if the target helo does not move during it's turn.. when a helo doesn't move, the game may consider it open to other than AAA attack as the helo is 'hovering' in place..
I've been able to shoot down helo's using the main gun of a tank before.. but only when the helo speed shows '0'.. once the helo moves - even evasive as a result of the tank firing - the tank can no longer shoot it's main gun, just any AA weapons that might be in range..
Have had the same thing happen using ATGM's also..
so - for those of you who have helo's.. if you think the opponent may be able to target you with anything other than AAA weapons, then move at least 1 hex.. this will insure that the helo won't become a lucrative 'hovering' target..
I have destroyed a helo with a main gun tank round but never with a ATGM, on the other hand I've had AAA's or SAM's that have spotted a helo but the game won't let me initate direct fire on them, Steve is movement on the part of the helo the reason for this also?