Arnie_Ze_Austrian wrote:
I'd ignore pretty much all of the fancy dropping guides where they tell you to use the altitude & HUD. Just play it by feel & experience. Most of the time you won't be flying level when dropping bombs (e.g. flying steady at 200 ft while ogling your HUD in an F-35B is a recipe for near instant death) and you'll be swooping down on the target instead. Like san4 said, the steeper your dive, the closer to the area the crosshair is over the bombs will land. I'd also try bombing in single drop mode in fighters. I can't get any decent accuracy in double drop mode unless I go near vertical because I have a habit of pulling up before the second bomb releases (meaning it flies off-target). Drop your bomb and switch to rear-view to see where it lands, then try dropping earlier/later or making your dive steeper if necessary.
It is certainly true that no guide can give you a hard and fast rule about how to aim bombs because your speed and angle are always changing.
That said, however, it is useful to have a starting point to practice with so you can develop the feel & experience. For me, at least, experience & feel tell me how much to deviate from my starting point of having the center of the HUD on the target while I'm diving.
Yes, flying straight at 200ft in an F-35B can get you killed, but it's a good starting point to practice bombing accurately (higher is safer and better for getting a steep dive). And looking behind you can be useful when practicing but it's very difficult for a new pilot to switch views while dropping bombs and pulling up. It is a useful thing to learn though, and it is essential for dogfighting.
Last, when you consider the advice people give about flying, see how many hours the advice-giver has in a plane. Arnie_Ze_Austrian & I have more than 50 hours (and we're not experts), but some of the other posters in this thread have minimal experience.