US will have to replace AIM-120 AMRAAMs and AIM-9 Sidewinders

⏩ US will have to replace AIM-120 AMRAAMs and AIM-9 Sidewinders
⏩ Missiles not fully compatible with F-35s and F-22s
⏩Illustrious Missiles reach a dead end
⏩US Pilots not fully confident of their efficacy against emerging challenges.


The AIM-120 Advanced Medium-Range Air-to-Air Missile or AMRAAM is a modern active radar homing beyond-visual-range air-to-air missile (BVRAAM) capable of all-weather day-and-night operations. It is 3.7 meter long and 7 inches (0.18m) in diameter.

The AIM-120D is an upgraded version of the AMRAAM with improvements in almost all areas, including 50% greater range (thought to be around 160km). The AIM-120D in fact is a development of the AIM-120C with a two-way data link, more accurate navigation using a GPS-enhanced IMU, an expanded no-escape envelope, and improved HOBS (High-Angle Off-Boresight) capability.

The AIM-9 Sidewinder is a short-range infrared homing or semi-active radar homing missile with a length of 3.02m and diameter of 5 inches (0.13m).

⏩PROBLEM: Probability of Kill (PK) of Missiles:

War games are a different ball game, where the pilot fires a simulated missile which shows up on a screen in a command center and judges then determine whether the missile is a kill or not. But in a real war scenario, AIM-120D might not have as excellent performance at the limits of their range especially against modern DRFM jammers. (Digital Radio Frequency Memory is an electronic method for digitally capturing and retransmitting Radio Frequency signals, designed to create a false target to a missile’s seeker)

Defence Express has reliably learned that combat record shows a kill rate for AIM-120 to be about 61 percent. Of course, AIM-120D is more advanced than previous models but then again a lot of kills were against aircraft that weren’t particularly capable with pilots that weren’t particularly well trained. Americans simply don’t know how it would hold against a capable adversary, say a Russian Su-35 or Su-57 for that matter. The second pointer for less than satisfactory PK of AMRAAMS against emerging challenges is that lot of Air Forces that would have earlier been game for them, are now preferring Meteors.

⏩Why not further upgrades of AMRAAMS and Sidewinders?

Russians are after all developing new variants of R-77 for Su-57, and AIM-9 has been updated several times. Then why not further upgrades of AIM-120 and AIM-9 as opposed to their replacement?

The answer is that AIM-9 and AIM-120 are not good for internal carriage. They are not volume efficient and can’t be packed into a bay like for example missiles with fold fins can. They can’t be stored, in tandem, like SDBs (Small Diameter Bombs) either.

⏩ Why not redesign the fins?

1. The redesigning of fins still will not allow you to pack the missiles in tandem in the bays. AIM-120 diameter is too small to allow for efficient utilization of the bays without something like a rack style launcher.

Best bet would be to build one missile that can fit in a 0.25m by 0.25m by 3.9m box, and another that has the same diameter but approximately half the length. This would efficiently use the bays of F-22 and F-35.

The F-22 side bays can be fitted to accept the smaller missile.


The AMRAAM like all weapons can only be upgraded to a point and some Americans are worried that AMRAAM is close to being ‘maxed out’.

There are several technologies desirable in a new air-to-air missile that upgraded AMRAAMS can’t incorporate.

One is multi-mode seeking. As enemy jammers get more advanced one solution would be to a missile that uses other seekers than just radar, including infrared and radiation.

This was the idea behind T3 missile though I’m pretty sure it’s been canceled.

Adding an anti-radiation mode would also allow it to replace the HARM as well.

There is also the possibility of using RAMJETS instead of traditional rocket motors although Raytheon has proposed a RAMJET variant of the AMRAAM called FMRAAM ( Future Medium Range Air-to-Air Missile ).

It is not yet known whether the FMRAAM will be produced since the target market, the British Ministry of Defence, has chosen the Meteor missile over FMRAAM for a BVR missile for the Eurofighter Typhoon.

But a RAMJET would be more efficient than a rocket motor and would allow the missile to fly slower as it cruised towards the target and then speed up in the terminal phase.

Finally, there is the possibility of designing a stealthier air-to-air missile. This was the idea behind the Have Dash Missile which was canceled with the end of the Cold War. A missile with a reduced RCS would give less warning to the target.

Read more: America’s F-35s, F-15s and F/A-18s Will Soon Have a New Bomb to Drop

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