noob,
Offline you can up a bomber box, set it on auto level flying say south at 5000ft. Then hop in the top or rear guns and pull up the offline target. Exactly what Lusche has posted in his pic. You can test it for yourself to become familiar with it.
By flying south you only need to know: .target 500 or any range you want.
It would be an interesting addition to the drones, if offline for bombers, you had a check box to include fighters that fly an attack pattern around your bomber or box of bombers. Besides feeding yourself to fighters in the MA. There are not many ways to learn bomber gunnery in terms of lead allowance. And probably the fighters would be limited to speed monsters, or your bombers would be speed limited once you auto leveled to trigger the appearance of the drones.
Maybe I should post this as a wish. For all of my gunsights, I'm a crappy bomber gunner.