Dunno if this will help but...
I cut the helis fuel when he is close to ground.... then give it back when I radio in.... and it never failed so far...
LOADATEXTRAC > HOLD > MOVETOBASE
^
|___ Syncronize with RADIO FOXTROT Trigger & Switch
(and give fuel to heli)
Problem is, heli might get to load and not wait for all members to get in, thats why I make sure its fuel its 0, when he gets really close to ground, and then give it back with radio. (you could also make him exec a script like heli addaction ["Lets go", "heligo.sqs"] in which you set his fuel to 1 and use a couple voices for nice effect
Just some thoughs.