The Weekly Debrief: Does Raytheon’s New AIM-120D3 Beat China’s Best Missile?
The U.S. Air Force advertised the Raytheon AIM-120D3 Amraam missile, which achieved a first guided launch test on June 30, as an upgrade for obsolete, two-decade-old electronics in the guidance section. The program has not improved the rocket motor or the propellant.
But now Raytheon executives say the latest version of the 44-year-old, radar-guided, air-to-air missile program has set two new time-of-flight records in the past 15 months. Paul Ferraro, president of Air Power for Raytheon Missiles and Defense, also told Aviation Week during an interview at the Farnborough Airshow that the recently demonstrated, extended time-of-flight means the AIM-120D3 boasts greater range than China’s radar-guided PL-15 missile.
The precise range of the domestic version of the PL-15 missile is not released, but its first public appearance in 2015 quickly provoked the U.S. Air Force to launch a new air-to-air missile program for the for the first time since the 1970s. In 2017, the Air Force secretly selected Lockheed Martin to develop the AIM-260 Joint Advanced Tactical Missile (JATM), with one top officer saying in 2019 that the new weapon formed the service’s response to the threat posed by the PL-15.
So what’s going on? Is it possible for Raytheon to extend the range of the venerable Amraam in an upgrade program that excludes any changes to the propulsion system? And if Raytheon’s claims are true, does the Air Force need the AIM-260?
Answering the last question is difficult amidst the secrecy that surrounds the performance details of all air-to-air missile programs, but some clues point to the timing of any decision between them.
But first, some background on the modern evolution of the AIM-120:
The Air Force conceived of the Amraam in the late-1970s, but the first AIM-120A became operational in September 1991. A decade later, the Air Force launched the first hardware refresh program for the AIM-120C7 missile. The original circuit boards in the Amraam were rectangular and installed longitudinally into the front half of the missile body. The refresh replaced these boards with hockey puck-style, circular circuit boards. By stacking the “pucks” in a row, the Air Force created empty space in the guidance section of the missile.
Beginning in 2007, the new AIM-120D development program exploited this extra space to extend the range of the missile. The additional performance did not come from a change to the propulsion system. Instead, the Air Force improved the navigational accuracy of the missile by installing a GPS system to augment the inertial navigation system. In combination with a new two-way datalink installed on the rear of the AIM-120D, the missile could guide itself more accurately during the fly-out stage, thus requiring fewer energy-bleeding corrections in the terminal phase.
A decade later, the Air Force decided it was time for another technical refresh. The Form, Fit and Functional Replacement (F3R) program was launched to replace 15 of the 30 circuit cards in the missile’s guidance system with modern hardware. The new cards use less energy, allowing the battery that powers the guidance system and seeker to function longer, Ferraro says. Now that the battery lasts longer, Raytheon can extend the time-of-flight of the missile.
The Air Force commissioned Raytheon to exploit the longer battery life with new software algorithms. The System Improvement Program (SIP)-3F, which was introduced last year, upgrades non-performance-related capabilities, such as the electronic-counter-countermeasures systems. SIP-4F, the next software release, will include new algorithms that optimize the guidance system to use the extended time-of-flight as the battery lasts longer, Ferraro says. Two successive flight tests since April 2021 of the AIM-120D3 with the F3R upgrades only proved the additional range of the longer battery life, and the SIP-4F software release will optimize that performance against future targets.
How the AIM-120D3 now compares against the performance goals of the AIM-260 program is impossible to know. Even the range of the potential threat is shrouded in mystery. China has advertised that the range of the export version of the PL-15 is 78 n.m. (145 km.), a range that may be intentionally misleading or merely degraded from the domestic version. (The range of any air-to-air missile also depends on the speed and altitude of the launch aircraft.)
One of the few details about the AIM-260 program that is known is the original schedule. As of June 2019, the Air Force expected to field the AIM-260 on the Lockheed Martin F-22 this year, and on the Boeing F/A-18E/F next year. So far, the Air Force and Lockheed have declined all requests since 2019 for updates on the schedule.
An Air Force spokeswoman said on July 25 that the AIM-260 will augment—not replace—the AIM-120, and “is needed to remain ahead of adversary air threat investments.”