How is Tracer ammunition useful?

[Fives]

All it does is that it only shows your location and they dodge it.

[BrigadierBill]

A few times tracers are nice:

1.) You can't catch up to an enemy fighter. I like to shoot tracers at them in order to make them do a bunch of panicked, ill-advised maneuvers, or at the very least maneuver enough that I start catching up again. If you have a few cannons on your aircraft, then firing MG tracers is no problem.

2.) They are shooting at a friendly fighter. If the target aircraft is trying to kill one of your teammates, then firing tracers will distract him and possibly force him to evade; if he continues on his course, then you know you'll have a clean shot when you get close.

3.) Fires. Tracers can cause fire damage more-readily than AP ammo can (although you're best off using I or IAI for that).

4.) Realistic/Simulator battles don't give you an aimer. If you don't know how far to lead your shots, then tracers give you an idea.

[KonCussive]

certain japanese 20mm tracer belts are pure HEI-T
which just overperforms other belts

[Quincy Jones]

Bill pretty much nailed it. If the Ki-45's 57mm cannon didnt have HEFI-T ammunition, I would not be able to hit anything, it's a slow projectile, which drops fast, and the cannon fires at a very slow rate with an ammo count of 15, you need all the help aiming that you can get.

[User]

Use OMNI belts, most of them have tracers on and also giving you some inc, AP rounds

[Procrastinating Gamer]

Best to just read the tooltip that comes up when you mouse-over a particular type of belt - it'll say what rounds are in that belt and what order they're in. Some nations just have ordinary tracers, while the Russians have tracer rounds that are also incendiary and armour-piercing rounds - so you get a clear view of where your shots are going, the rounds can punch through a fair bit of armour plating and they've a good chance of setting something on fire if you hit anything flammable in there - and as others have said; Japanese tracers are high-explosive incendiary rounds.

A tracer round from a rifle is nothing special, a tracer round from an aircraft is a different sort of beast.