As long as you are in the bombing run when they kill someone you will be given credit for achieving this.
Another strategy here is to bomb the trailer you enter for the bomber.
I would start with the defibrillator as it will be the hardest one to complete.
For the "Open Fire" assignment you need the three assault rifle ribbons before the other three requirements.
Many times enemies will be waiting for you to come out and make themselves an easy target.
Just be careful, if you are in hardcore you can kill teammates or yourself if you leave the trailer before the bombs hit.After playing more and more hours, here is another strategy.When you get in the bomber let your first 3 missiles fly right away in the direction of where you think the enemy is.Most people find a boosting partner to just fly the edges of the map and help each other get the kills.You just have to watch for other people enjoying the fact someone is just sitting these waiting to be killed. Earn 3 Assault Ribbons, then: You Need a kill with a Pistol, a 40MM Grande, and the Defibrillator all in one round.The requirements that say "in a round" must all be done in the same round to stick.For the L85 you need a defibrillator, pistol, and M320 40mm grenade kill all in the same round. You can do any of these in any map other than the bombers as they are only on the China Rising maps at this time.You will earn this one en-route to earning Death From Above On the China Rising Maps there is a trailer that will show a plane on it from time to time, normally near location C on PS3 and "D" on PS4 in conquest matches.When it shows this plane, approach the trailer from the side with the stairs and hit when prompted to enter the trailer. To release the JADM, find your target(s) and use to release the weapon.It does take a few moments to get there, so lead your target if it is moving.