Source : Wiki AIM-120 page
Kill probability and tactics
Once in its terminal mode, the missile's advanced electronic counter countermeasures (ECCM) support and good maneuverability mean that the chance of it hitting or exploding close to the target is high (on the order of 90%), as long as it has enough remaining energy to maneuver with the target if it is evasive. The kill probability (Pk) is determined by several factors, including aspect (head-on interception, side-on or tail-chase), altitude, the speed of the missile and the target, and how hard the target can turn. Typically, if the missile has sufficient energy during the terminal phase, which comes from being launched close enough to the target from an aircraft flying high and fast enough, it will have an excellent chance of success. This chance drops as the missile is fired at longer ranges as it runs out of overtake speed at long ranges, and if the target can force the missile to turn it might bleed off enough speed that it can no longer chase the target.
 Lower-capability targets
This leads to two main engagement scenarios. If the target is not armed with any medium or long-range fire-and-forget weapons, the attacking aircraft need only to get close enough to the target and launch the AMRAAM. In these scenarios, the AMRAAM has a high chance of hitting, especially against low-maneuverability targets. The launch distance depends upon whether the target is heading towards or away from the firing aircraft. In a head-on engagement, the missile can be launched at longer range, since the range will be closing fast. In this situation, even if the target turns around, it is unlikely it can speed up and fly away fast enough to avoid being overtaken and hit by the missile (as long as the missile is not released too early). It is also unlikely the enemy can outmaneuver the missile since the closure rate will be so great. In a tail-on engagement, the firing aircraft might have to close to between one-half and one-quarter maximum range (or maybe even closer for a very fast target) in order to give the missile sufficient energy to overtake the targets.
If the targets are armed with missiles, the fire-and-forget nature of the AMRAAM is invaluable, enabling the launching aircraft to fire missiles at the target and subsequently take defensive actions. Even if the targets have longer-range semi-active radar homing (SARH) missiles, they will have to chase the launching aircraft in order for the missiles to track them, effectively flying right into the AMRAAM. If the target aircraft fires missiles and then turn and runs away, their own missiles will not be able to hit. Of course, if the target aircraft have long range missiles, even if they are not fire-and-forget, the fact that they force the launching aircraft to turn and run reduces the kill probability, since it is possible that without the mid-course updates the missiles will not find the target aircraft. However the chance of success is still good and compared to the relative impunity the launching aircraft enjoy, this gives the AMRAAM-equipped aircraft a decisive edge. If one or more missiles fail to hit, the AMRAAM-equipped aircraft can turn and re-engage, although they will be at a disadvantage compared to the chasing aircraft due to the speed they lose in the turn, and would have to be careful that they're not being tracked with SARH missiles.
 Similarly armed targets
The other main engagement scenario is against other aircraft with fire-and-forget missiles like the Vympel R-77 (NATO AA-12 "Adder") — perhaps MiG-29s, Su-27s or similar. In this case engagement is very much down to teamwork and could be described as "a game of chicken." Both flights of aircraft can fire their missiles at each other beyond visual range (BVR), but then face the problem that if they continue to track the target aircraft in order to provide mid-course updates for the missile's flight, they are also flying into their opponents' missiles. Although in this regard the RVV-AE (which is the missile's export name or R-77 the official Russian Air force designation) does have an advantage as it has a greater range than the AMRAAM (when the AIM-120D is deployed the AMRAAM will have 30+ miles more range than the R-77, and with stealth planes such as the F-22 Raptor the range of the enemies weapons doesn't matter), meaning that the Russian airplane firing it can in fact fire first, although it still needs to lead the missile towards the target as the missiles own radar seeker has a limited range (under 10 km for the R-77, and longer range for the AMRAAM). This is why teamwork is so important and advanced missiles with guidance systems with hand-off capability can help overcome this problem. This is also part of the reason why most tactics dictate holding on to missiles "until you see the whites of their eyes," or holding on to them for as long as possible.
If the enemy fires missiles at maximum range, you will be able to defeat them easily without having surrendered valuable ordnance yourself. The other main tactic would be to sneak up behind the enemy aircraft and launch missiles without them noticing, giving the launching aircraft sufficient time to leave the danger zone of the enemy after launching. Even if the enemy detects the launch and turns around, the speed and possibly altitude it loses during the turn puts its missiles at an energy disadvantage which may be sufficient for the other aircraft to defeat it. This typically requires excellent ground-control intercept (GCI) or airborne radar (AWACS) facilities in order to be successful.