Can current air to air missiles shoot each other down?

Question

Assuming that a missile is able to track, lock and effectively guide itself to another missile for sake of argument, would say an AIM 9X or AIM120 be able to shoot down its respective counterpart?

Note the AIM 9X and AIM 120 are just examples, I'm talking about in general. Air launched air to air missiles are the scope of the question. So anti-ballistic missiles, cruise missiles etc are out of scope.

The reason I ask is because active protection systems against kinetic energy penetrators, especially depleted uranium rounds, face significant challenges in achieving hardkill. An APS system isn't going to do much other than breaking it up a bit or causing the incoming round to tumble or wobble. Either way an APFSDS round is smashing against hull armor and punching a nasty gash at the very least. Speed is one of the issues that make APS systems ineffective compared to stopping HEAT.

Missiles on the other hand are launched way higher in the sky, with a high initial velocity and a powerful rocket motor. While the motor quits eventually, there's still a lot of kinetic energy. However, missiles are more beholden to the laws of aerodynamics and loss of kinetic energy. I'm not entirely sure if blast frag or a continuous rod warhead could expand fast enough to cut up a missile. Or if there was non catastrophic damage, would the damaged missile body and fins allow a missile to still limp its way to a target for a successful kill, or would the missile bleed kinetic energy like crazy eventually falling out or self detonating.

Answer 1

Yes they can, although they might have a hard time doing so.

General

Generally speaking, a missile searches for a suitable signal source which it tries to hit, e.g. an IR source such as an engine, or a radar return. Once aquired it alters its trajectory such that it hits the signal source. Therefore for a missile it is no different if the heat source it tracks is the hot turbine engine of another jet, or the (still) hot rocket engine of another missile. The same hold for radar guided missiles.

Example

I think a good example is that of the Diehl IRIS-T Anti-Air missile. Originally conceived as an air-to-air missile, it has been converted to an surface-launched anti-air missile by mainly upgrading the rocket engine, therefore equipping that missile with more energy. This missile was recently deployed to Ukraine in order to defend against incoming missiles. While the missiles the IRIS-T is defending are not typically air-to-air missiles, it shows that a (converted) anti-air missile is capable of hitting another missile.

Physics constraints

However one has to realize that an air-to-air missile is not a good fit to shoot down another air-to-air missile. Both missiles are roughly equally fast and equally maneuverable, however typically you would want your defending missile to have an advantage of higher maneuverability (a value I heard often is 3 times more maneuverable) then your enemy. Additionally, the flight time even of long range A/A missiles is short (at longest a couple of minutes), making targeting and tracking difficult. The angle at which the incoming missile can be tracked and killed is small, the position from which the defending missile has to be launched is narrow. Therefore your defending missile is not as likely to hit the enemy missile

Effector

I am no expert in this, however consider this: Even small holes or damages create huge air-drag at a speed of mach 3. Therefore if you manage to damage the enemy missile even slightly (perhaps a couple of holes, or half a fin), I would say that this missile is doomed.

Answer 2

When you design a missile, a significant part of the parameters are based on "what are you trying to kill?" The effort needed to disable an aircraft in order to knock it out of the sky is quite different from that needed to destroy a missile.

The processing speed of the computers inside your missile also limit the upper speed that you can track. In the past, designers used to also specify the lower speed limits - the widespread introduction of helicopters put an end to it. During WW2, there were stories of mechanical computers (used for aiming anti-aircraft guns) on board naval vessels being unable to target some torpedo bombers because the aircraft travelled slower than the computers were designed to handle.

This video shows a reconstruction of the shootdown of Malaysian Airlines flight 17 over Ukraine. Missiles do not impact the target as if they were large bullets. Instead they detonate nearby and shred the target with shrapnel. The only aircraft that I am aware of that are designed to survive in an environment full of shrapnel are ground attack aircraft such as the A-10. For these aircraft, fuel consumption is irrelevant. For passenger aircraft, fuel consumption is the most important operating characteristic that airlines measure. As missiles are far more compact than aircraft, they are harder for the shrapnel cloud to affect and will therefore sustain far less damage than human occupied aircraft.