In air-to-air combat, BVR missiles fill the niche of old battle rifles and modern sniper rifles, WVR missiles fill the niche of modern assault rifles, while gun fills niche of combat knife. While gun is most versatile weapon of the lot – it can be used for air-to-air work, close air support, firing warning shots towards aircraft violating forbidden airspace – it is not often used in air-to-air combat and is treated purely as fallback weapon in case missiles have been expended.
It is often forgotten is that g forces in tracking turn are a square of speed. Thus, in WVR combat, if missile travels at Mach 3 and fighter aircraft travels at Mach 0,6 (corner speed of many modern fighters) and can pull 9 g maneuvers, then missile needs to pull 225 g to match turn radius, or 100 g if fighter is travelling at Mach 0,9. If missile is fired outside ideal position, it has to maneuver in order to point its nose towards the target, thus lowering probability of kill; there is also a danger of targeted aircraft simply flying out of missile’s field of view. This danger is also present with active-seeker BVR missiles. In BVR, AIM-120 travels at Mach 4, and can pull 30 g within its NEZ, yet it would need 400 Gs to reliably hit a modern fighter which is maneuvering at corner speed of Mach 0,6, or 178 Gs if target is still at standard cruise speed of Mach 0,9.
Further, even though BVR missiles have maximum range of over 100 kilometers, their effective range against aircraft in attack is 1/5 of that – around 20 kilometers – and target beyond 40 kilometers can feel free to maneuver without even taking any possible missile shots into account, as only way these would hit is luck. One of reasons is that BVR missiles follow ballistic trajectories – AIM-120C-5 allegedly has motor burn time of 8 seconds, which gives range of around 10 kilometers before motor burns out. At ranges greater than 8 kilometers, attacking fighter can still choose wether to outmaneuver or outrun the BVR missile; at distances less than that is missile’s no-escape zone, where aircraft cannot outrun the missile, it has to outmaneuver it, but such distances automatically mean that combat is not longer beyond visual range. Ranges stated are also only true at high altitude against aircraft in attack; at low altitude, effective range of BVR missile is reduced to 25% of its range at high altitude, and range against aircraft in flight is 1/4 of that against aircraft in attack.
Missiles in fact can achieve either maximum range or maximum maneuvering capability – missile that pulls 40 g at sea level will only pull 13 g at 10.000 meters and 2,85 g at 20.000 meters, unless 40 g is a structural limit. AIM-9 for example can pull 40 g at SL and at 10.000 ft, and 35 g at 20.000 ft. Thus, it can be expected to pull single-digit number of g’s at 40.000 ft. Meanwhile, F-16 for example can sustain 8,5 g at 15.000 ft, and Rafale can sustain 9 g at 40.000 ft.