Testing of the Air Force's scramjet-driven Hypersonic Attack Cruise Missile — known by the designation HACM — has advanced to live flight evaluation, with documentation pointing to at least one airborne drop conducted over an Australian test range. Schedule constraints on the HACM programme have led planners to narrow the breadth of testing, a step taken to prevent additional delays from accumulating.
Plans call for a procurement decision on HACMs to be reached by 2027, at which point volume acquisition would begin. Joint development of HACM has brought the Air Force and Australia's Royal Australian Air Force together as programme partners, with part of the work taking place within the joint framework of the U.S.-Australian Southern Cross Integrated Flight Research Experiment, known as SCIFiRE.
Work on the HAWC programme — a DARPA-led effort to develop air-breathing hypersonic weapons — fed directly into the development of HACM. A joint development contract for the missile was awarded in 2022 to RTX — the company formerly operating as Raytheon — alongside partner Northrop Grumman. The weapon has reportedly received the designation AHM-4A under a newly established category within the joint service nomenclature framework covering aircraft and missiles.
No determination has been made about whether the missile sustained independent propulsion at any point following its separation from the aircraft. The type of aircraft used to lift the missile into the air has not been determined.
Plans for HACM test launches to be carried out on Australian soil had been disclosed by the Air Force at an earlier point. Woomera Test Range has long been viewed as the intended venue, given its capacity to accommodate the extended flight-testing distances that such work demands. Joint hypersonic trials at the Woomera test range have drawn both nations into collaborative work on prior occasions.
Documents filed by the Government Accountability Office — a watchdog body that answers to Congress — indicate that F/A-18F Super Hornets operated by the Royal Australian Air Force would carry out at least a portion of the planned HACM test launches. Planned as the first delivery platform for that capability, the F-15E Strike Eagle carries the Air Force's rollout forward, with additional aircraft types anticipated to join the programme over time.
As of now, no confirmed image or technical rendering of HACM has been made public by either the Air Force or Raytheon. The weapon's architecture, as outlined in a Government Accountability Office report, pairs a rocket booster with a scramjet-powered cruiser section that detaches mid-flight and steers toward its intended target; a photograph published by the Air Force in 2023 depicted a test article linked to that propulsion line, connected to either the Hypersonic Attack Cruise Missile program or the earlier Hypersonic Air-breathing Weapon Concept effort that preceded it.
Because scramjets only generate thrust efficiently above a certain threshold velocity, any vehicle relying on them requires an auxiliary propulsion stage to push it up to the required Mach number before the engine can take over. While Mach 5 serves as the conventional lower boundary for hypersonic flight, the top speed HACM can actually reach has not been made public.
Prototype runs of dual-stage, air-breathing hypersonic vehicles shaped along missile-like lines have taken place on a number of prior occasions. Among the test platforms covered are Boeing's scramjet-driven X-51 Waverider and the HyFly 2 hypersonic vehicle, alongside a number of additional experimental craft. Building aircraft and missiles around scramjet propulsion has long presented engineers with a set of persistent technical hurdles.
Scheduling setbacks have accumulated at HACM across multiple periods. Planners had originally set 2024 as the target year for a first flight, a date that moved to 2025 and later to 2026; the HACM programme now appears positioned to meet that updated window in the second quarter of fiscal year 2026, though programme officials noted that no buffer remains in the rapid prototyping timeline.
The watchdog agency's July findings noted that the Air Force had already trimmed the number of planned flight tests under the rapid prototyping phase from seven down to five, with 13 missiles slated for production across that effort — covering test assets, spares, and operational rounds — and warned that a notable failure during testing would likely prevent all five evaluations from being completed within the five-year window. The first three tests were described by the program as essential for informing a decision to advance to rapid fielding and begin procuring HACM in fiscal year 2027, with that fielding phase targeted to begin in the first quarter of that year, leading the report to conclude that the program had accepted schedule risk to hold its current timeline.
Program officials told the GAO that keeping to the schedule has meant running activities in parallel — including parts validation testing alongside ongoing design work — a practice that leaves the door open to part redesigns if validation results fall short. Beyond scramjet-driven systems such as HACM, other categories of hypersonic missile under development in the United States have faced their own sets of obstacles.
Weapons programs spread across the Air Force, Navy, and Army — each aimed at fielding hypersonic missiles capable of launching from the air or from the ground — ran into repeated obstacles over the course of the past ten years. Cancellation of the Navy's own air-launched hypersonic cruise missile programme — formally designated Hypersonic Air-Launched Offensive Anti-Surface Warfare, or HALO — opened the door for funding and focus to shift toward the Blackbeard missile, which sits at the centre of a follow-on effort called the Multi-mission Affordable Capacity Effector, or MACE.
Funding, too, remains a consideration within the programme's broader context. The programme's origins date to an era when hypersonic missiles were broadly understood to be formidable yet expensive weapons available only in limited numbers. The Blackbeard programme sits within a broader drive to bring weapons designs to the field that are both cheaper to procure and easier to manufacture in large quantities.
Both the American and Australian militaries have identified hypersonic weapons as a key factor in their readiness for future armed confrontations, with particular attention directed toward high-end scenarios across the Pacific region. Proponents argue that air-breathing hypersonic cruise missiles can reach distant targets at speed, though assessments of their operational range and effectiveness vary among analysts. Velocity and agility built into the system's design are cited as enabling it to slip past defensive countermeasures while leaving opposing forces with a narrower window in which to mount a response.
Reaching even a limited production milestone for HACM before the end of 2027 would mark a shift in direction for a programme whose development schedule has slipped on multiple occasions. Questions about the structure of any opening deployment — and how a condensed testing schedule might alter that — remain unresolved.
