Everything about Aim-120 Amraam totally explained
The
AIM-120 Advanced Medium-Range Air-to-Air Missile, or
AMRAAM (pronounced am-ram), is a modern
Beyond Visual Range (BVR) air-to-air missile (AAM) capable of all weather day and night performance. It is also commonly known as the
Slammer in USAF service. When an AMRAAM missile is being launched,
NATO pilots use the
brevity code Fox Three in radio communication, as with all active-guidance missiles.
Origins
AIM-7 Sparrow MRM
The
AIM-7 Sparrow medium range missile (MRM) was developed by the US Navy in the 1950s as its first operational BVR air-to-air weapon. With an effective range of about, it was introduced as a radar
beam riding missile and then improved to a
semi-active radar guided missile which would home in on reflections from a target illuminated by the radar of the launching aircraft. It was effective at visual to beyond visual range. The early beam riding versions of the Sparrow missiles were integrated onto the
F3H Demon and
F7U Cutlass, but the definitive AIM-7 Sparrow was the primary weapon for the all weather, gun-less
F-4 Phantom II fighter/interceptor with up to four carried in special recesses under the fuselage.
Although designed for non maneuvering targets such as bombers, due to poor performance against fighters over North Vietnam, these missiles were progressively improved until they proved effective in dogfights. Together with the short range infrared guided
AIM-9 Sidewinder, they replaced the
AIM-4 Falcon IR and radar guided series for use in air combat by the USAF as well. A disadvantage to semi-active homing was that only one target could be illuminated by the launch aircraft at a time; also, the launch aircraft had to remain pointed in the direction of the target (within the azimuth of the aircraft radar, up to 60 degrees off the nose on some systems), which could be difficult or dangerous in combat.
AIM-54 Phoenix LRM
The US Navy later developed the
AIM-54 Phoenix long range missile (LRM) for the fleet air defense mission. It was an impressive Mach 5 missile designed to counter cruise missiles and their (Bomber) launch platforms. It was intended that eight of its first incarnation would be fitted to the straight-wing
F6D Missileer, and then the
F-111B. Neither aircraft was introduced into service and Grumman won the competition to replace the F-111B with a dogfighter with enough weight and volume for the Phoenix that became the
F-14 Tomcat. Phoenix was the first US
fire-and-forget multiple launch radar-guided missile: one which used its own active guidance system to guide itself without help from the launch aircraft when it closed on its target. This gave a Tomcat with a six Phoenix load the unprecedented capability of tracking and destroying up to six targets as far as away.
The Phoenix could only be carried by the huge F-14, making the Tomcat the only US fighter with a multiple shot, fire-and-forget radar missile. A full load of six Phoenix weighed, and with the additional of dedicated launcher, it was so heavy it exceeded a typical Vietnam era bomb load; typically only two or four missiles were flown off the carrier as a full load was too heavy to be brought back on board for landing. Although highly lauded in the press, its operational service with the US Navy was primarily as a deterrent as its use was hampered by restrictive
Rules of Engagement and the only reported combat successes were with Iranian Tomcats against Iraqi opponents. The US Navy retired its Phoenix capability in 2005 in light of availability of the AIM-120 AMRAAM on the
F/A-18 Hornet.
ACEVAL/AIMVAL
The
Department of Defense conducted an extensive evaluation of air combat tactics and missile technology from 1974-78 at
Nellis AFB using the F-14 Tomcat and F-15 Eagle equipped with Sparrow and Sidewinder missiles as blue force and Aggressor F-5E aircraft equipped with
AIM-9L all-aspect Sidewinders as the Red force. This
Joint Test and Evaluaton JT&E was designated
Air Combat Evaluation/
Air Intercept Missile Evaluation (
ACEVAL/
AIMVAL)
(External Link
). A principal finding was the necessity to produce illumination for the Sparrow until impact resulted in the Red Force being able to launch their all-aspect Sidewinders before impact thereby resulting in mutual kills. What was needed was Phoenix type multiple launch and terminal active capability in a Sparrow size airframe. This led to a
Memorandum of Agreement (MOA) with European allies (principally the UK and Germany for development) for the US develop an
Advanced Medium Range Air-to-Air Missile with the USAF as lead service. The MOA also assigned responsibility for development of an Advanced Short Range Air-to-Air Missile to the European team.
Requirements
By the 1990s, the reliability of the Sparrow had improved so much from the dismal days of Vietnam that it accounted for the largest number of aerial targets destroyed in
Desert Storm, and proved effective against the Mach 3
MiG-25 Foxbat. But while the USAF had passed on the Phoenix and their own similar
AIM-47/
YF-12 to optimize dogfight performance, they still desired the Navy's multiple launch fire and forget capability for the F-15 and F-16. AMRAAM would need to be fitted on fighters as small as the F-16, and fit in the same spaces that were designed to fit the Sparrow since the Phantom. The European partners needed AMRAAM to be integrated on aircraft as small as the Sea Harrier. The US Navy needed AMRAAM to be carried on the F/A-18 Hornet and wanted capability for two to be carried on a launcher that normally carried one Sparrow to allow for more air-to-ground weapons.
AMRAAM would eventually be the primary weapon for the
F-22 Raptor which needed to fit all its missiles in internal weapons bays like the old
F-106 Delta Darts in order to maintain a stealthy
radar cross-section. The US Navy ultimately decided to retire its Tomcats and pass the Fleet Air Defense mission to the F/A-18C and F/A-18E/F Hornets, which needed even more advanced versions of AMRAAM to replace the Phoenix capability.
Development
AMRAAM was developed as the result of an agreement, the
Family of Weapons Memorandum of Agreement no longer in effect by 1990, among the United States and several other
NATO nations to develop air-to-air missiles and to share production technology. Under this agreement the U.S. was to develop the next generation medium range missile (AMRAAM) and Europe would develop the next generation short range missile (
ASRAAM). When the German ASRAAM seeker development ran into problems, the MOA was abrogated and this breakdown led to the U.S. developing
AIM-9X Sidewinder and Germany the
IRIS-T. Although Europe initially adopted AMRAAM, an effort to develop the
MBDA Meteor, a competitor to AMRAAM was begun. Eventually ASRAAM was developed solely by the UK with another source for its seeker. After protracted development, deployment of AMRAAM (AIM-120A) began in September 1991 began with USAF F-15 Eagle squadrons. The US Navy followed suit in 1993 with the F/A-18C.
The eastern counterpart of AMRAAM is the very similar
Russian R-77 AA-12 Adder, commonly known in the west as "AMRAAMski." Likewise, France began its own missile development with the
MICA concept that used the same airframe for separate radar and IR guidance versions.
Operational features summary
AMRAAM has an all-weather, beyond-visual-range (BVR) capability. It improves the aerial combat capabilities of U.S. and allied aircraft to meet the future threat of enemy air-to-air weapons. AMRAAM serves as a follow-on to the
AIM-7 Sparrow missile series. The new missile is faster, smaller, and lighter, and has improved capabilities against low-altitude targets. It also incorporates a datalink to guide the missile to a point where its active radar turns on and makes terminal intercept of the target. An inertial reference unit and micro-computer system makes the missile less dependent upon the fire-control system of the aircraft.
Once the missile closes in on the target, its active
radar guides it to intercept. This feature, mistakenly called "
fire and forget," frees the aircrew from the need to further provide guidance, enabling the aircrew to aim and fire several missiles simultaneously at multiple targets and perform evasive maneuvers while the missiles guide themselves to the targets.
The missile also features the ability to "Home on Jamming," giving it the ability to switch over from active radar homing to passive homing - homing on jamming signals from the target aircraft. Software on board the missile allows it to detect if it's being jammed, and guide on its target using the proper guidance system. This, contrary to the attack sequence on a non-jamming target, truly can be described as "
fire and forget", as it doesn't require any guidance provided to the missile after launch.
Guidance system overview
Interception course stage
AMRAAM uses two-stage
guidance when fired at long range. The aircraft passes data to the missile just before launch, giving it information about the location of the target aircraft from the launch point and its direction and speed. The missile uses this information to fly on an interception course to the target using its built in
inertial navigation system (INS). This information is generally obtained using the launching aircraft's
radar, although it could come from an
infra-red search and tracking system (
IRST), from a
data link from another fighter aircraft, or from an
AWACS aircraft.
If the firing aircraft or surrogate continues to track the target, periodic updates are sent to the missile telling it of any changes in the target's direction and speed, allowing it to adjust its course so that it's able to close to self-homing distance while keeping the target aircraft in the
basket (the radar seeker's field of view) in which it'll be able to find it.
Not all AMRAAM users have elected to purchase the mid-course update option, which limits AMRAAM's effectiveness in some scenarios. The
RAF initially opted not to use mid-course update for its
Tornado F3 force, only to discover that without it, testing proved the AMRAAM was less effective in BVR engagements than the older
semi-active radar homing BAE Skyflash weapon—the AIM-120's own radar is necessarily of limited range and power compared to that of the launch aircraft.
Terminal stage and impact
Once the missile closes to self-homing distance, it turns on its active radar seeker and searches for the target aircraft. If the target is in or near the expected location, the missile will find it and guide itself to the target from this point. If the missile is fired at short range (typically, visual range), it can use its active seeker just after launch, making the missile truly
fire-and-forget. At the point where an AMRAAM switches to autonomous self-guidance, the NATO
brevity code "PITBULL" would be called out on the radio, just as "Fox Three" would be called out upon launch.
Kill probability and tactics
General considerations
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's evasive. The
kill probability (P
k) 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'll 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 isn't 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's unlikely it can speed up and fly away fast enough to avoid being overtaken and hit by the missile (as long as the missile isn't 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 then turn and run away. Even if the targets have longer-range
semi-active radar homing (
SARH) missiles, that'll 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 won't be able to hit. Of course, if the target aircraft have long range missiles, even if they're not
fire-and-forget, the fact that they force the launching aircraft to turn and run reduces the kill probability, since it's possible that without the mid-course updates the missiles won't 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 that'll 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're also flying into their opponents' missiles. 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'll 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 — Airborne Warning and Control System) facilities in order to be successful.
Variants and upgrades
Air-to-air missile versions
There are currently three variants of AMRAAM, all in service with the
United States Air Force and
USN. The AIM-120A is no longer in production and shares the enlarged wings and fins with the successor AIM-120B currently in production. The AIM-120C has smaller "clipped" aerosurfaces to enable internal carriage on the USAF
F-22 Raptor. AIM-120B deliveries began in 1994, and AIM-120C deliveries began in 1996.
The AIM-120C has been steadily upgraded since it was introduced. The AIM-120C-6 contained an improved fuse (Target Detection Device) compared to its predecessor. The AIM-120C-7 development began in 1998 and included improvements in homing and greater range (actual amount of improvement unspecified). It was successfully tested in 2003 and is currently being introduced into active service (early 2005). It helped the
U.S. Navy replace the
F-14 Tomcats with
F/A-18E/F Super Hornets – the loss of the
F-14's long-range
AIM-54 Phoenix missiles (already retired) can be partially offset with a longer-range AMRAAM, but note that the AMRAAM doesn't have a longer range than the Phoenix.
The AIM-120D is a planned upgraded version of the AMRAAM with improvements in almost all areas, including 50% greater range (than the already long range AIM-120C-7) and better guidance over its entire flight envelope yielding an improved kill probability (
PK).
There are also plans for
Raytheon to develop a
Ramjet-powered derivative of the AMRAAM, the Future Medium Range Air-Air Missile (FMRAAM). It isn't known whether the FMRAAM will be produced since the target market, the British Ministry of Defence has chosen the
Meteor missile over the FMRAAM for a
BVR missile for the
Eurofighter Typhoon aircraft.
Ground-launch systems
Raytheon successfully tested launching AMRAAM missiles from a five-missile carrier on a
HMMWV (hum-vee). They receive their initial guidance information from a radar not mounted on the vehicle (probably the
MPQ-64 Sentinel radar system or possibly a
PATRIOT missile battery radar) and help to provide low-level, close-in defence while the PATRIOT system engages targets at higher altitudes and further ranges. The missile's range would be lower when launched from the ground, due to the lack of speed or altitude of the launch vehicle. This system will be known as the
SLAMRAAM (Surface Launched (SL) and AMRAAM).
The
Norwegian Advanced Surface-to-Air Missile System (NASAMS), developed by
Kongsberg Defence & Aerospace, consists of a number of vehicle-pulled launch batteries (containing six AMRAAMs each) along with separate radar trucks and control station vehicles.
Operators
Royal Australian Air Force
Belgian Air Component
Royal Bahraini Air Force
Canadian Forces Air Command
Chilean Air Force
Czech Air Force
Danish Air Force
Finnish Air Force
Luftwaffe
Hellenic Air Force
Hungarian Air Force
Israeli Air Force
Italian Air Force
Italian Navy
Royal Jordanian Air Force
Republic of Korea Air Force
Royal Malaysian Air Force (120-C5)
Royal Netherlands Air Force
Royal Norwegian Air Force
Royal Air Force of Oman (RAFO)
Pakistan Air Force
Polish Air Force
Portuguese Air Force
Republic of China Air Force
Republic of Singapore Air Force
Swiss Air Force
F-15S
Spanish Air Force
Spanish Army
Spanish Navy
Swedish Air Force
Royal Thai Air Force
Turkish Air Force
Royal Air Force
United States Air Force
United States Navy
United States Marine Corps
In early 2006 the Pakistan Air Force ordered 500 AIM-120C-5 AMRAAM missiles as part of a $650mn F-16 ammunition deal to equip the PAF's F-16C/D Block 52+ and F-16A/B MLU.
In 2005 Chile received AIM-120 AMRAAM missiles from the United States Air Force as part of the Peace Puma Plan which Chilean Air Force also received 10 F-16 D fighters as part of the plan. In 2006 Poland new F-16 Block52+ has Aim-120C-5.
In 2007, the United States government agreed to sell 218 AIM-120C-7 missiles to Taiwan as part of a large arms sales package that also included 235 AGM-65G-2 Maverick missiles. Total value of the package, including launchers, maintenance, spare parts, support and training rounds, was estimated at around $421 million USD. This supplemented an earlier Taiwanese purchase of 120 AIM-120C-5 missiles a few years ago.
Further Information
Get more info on 'Aim-120 Amraam'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://aim-120_amraam.totallyexplained.com">AIM-120 AMRAAM Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
