Decided to go after setting a record that should be tough to beat. It takes a lot of time and patience to do this one. You have to kill as many enemies as possible in one chopper ride. This means you can change choppers or land or it stops counting.
You want to use the attack chopper with the missiles. You can find some spots that will allow you to shoot without the enemies calling in reinforcements.
Find a spot that cars cant get below you, especially tanks. At certain heights they won’t call in naval forces.
You want to have a friendly base with a SAM site close by in case you get too many choppers coming at you.
You want to attack towns not bases
You want to keep your Heat level at 2 or below (thats the patience part)
At 600 kills I got hit by a chopper so was spewing smoke and the controls were hard to hold still to aim. I was tired so I decided to call it a day at 910 kills.