okay i know how he did this,
(this is a joke, if you think im serious i classify you a nub)
either,
1. get hit by a moving chopper,
2. you hit the chopper and go flying xD
3. run into a crashing chopper then get launched into the air x] << my favorite lol!
4. you jumped out of a moving heli and was like OMG!! lolz fly1ing hahah
5. you jumped off a cliff while the chopper is right under you and ZOOOM you go lmao!
cant think of any others, feel free to add on
6. you ran onto a roof of a glitch then fell under the game map, and then SLINGSHOT into the sky lmao!