Missiles versus aircraft is a fight between very high kinetic energy in the missile, and relatively low kinetic energy in the plane, but with the ability to generate more kinetic energy. Missiles don't have a lot of fuel, so they need to generate a lot of kinetic energy to still be effective by the time they reach the target. Typically a missile will accelerate to its top speed in the first few seconds of flight and coast the rest of the way. At very long ranges, all the energy generated when launched has bled off, so there's two common solutions for long-range missiles to generate more energy: a "dual pulse" motor is basically a second rocket motor that fires later in the course; or a ramjet, which can be throttled up and down and is more fuel efficient than a rocket engine.

A ramjet drastically increases range against maneuvering targets. The 'maximum range' quoted for missiles like the AIM-120D (Likely 140-170km) is normally for a front on shot at extremely high altitude (10-15km+) with no evasive actions. With an evading target the No Escape Zone (where a target likely can't kinetically evade the missile) will only be 15-25km.

The Meteor has a longer sustainer and a terminal boost meaning that the No Escape Zone is though to be upwards of 60km. Qatar might have used Meteors to shoot down Iranian Su 24's just a few months ago based on the range they were shot at.

You really need to play combat flight sims (like DCS) to understand why a ramjet AA missile makes a lot of sense ;)

It's not mainly about top speed, but about endurance (e.g. flying under power for the entire flight time of the missile).

The gist ist that traditional BVR AA missiles are only powered at the start of an engagement (and a lot of that power is used to gain height) until their rocket engine runs out of fuel. For a large part of its flight, traditional AA missiles glide without power towards the target, meaning the missile will lose speed from the moment the rocket engines are switched off, and even more for each required maneuver that needs to be performed afterwards (that's why it is a valid strategy for the targeted airplane to evade the missile by forcing it into a turn during its unpowered flight phase - e.g. instead of doing a 180 and flying straight away from the missile, fly a roughly 90 degree course to the incoming missile to force it into a wide turn, which means the missile will lose more energy than it would when remaining on a straight course).

A ramjet powered missile on the other hand flies under power for the entire engagement, it can 'cruise' towards the target and then for the final phase of the engagement speed up and home in on the target (or generally do complex maneuvers) without losing speed, which gives the target airplane much fewer options to evade the attack.

> I read some funny commentary once about how to shoot down a modern fighter jet: Two missiles. They can dodge the first one, but sacrifice so much speed, that the second one can easily find its target.

With a ramjet missile you don't need a second missile to exploit the target's depleted energy. And the two-missile strategy also doesn't really work when the other aircraft fires a single Meteor from a greater distance first ;)

It's not that simple. If the target aircraft is outside the minimum abort range then they can still evade multiple missiles, regardless of whether the shooting platform or the missiles themselves are locked on. Typically they would do so by descending into denser air and beaming the missile to bleed its limited energy. On larger missiles a ramjet can potentially allow it to retain more energy into the terminal phase.

There are a variety of other defenses including countermeasures, signature reduction, EW, and decoys which also complicate the issue.