US Arctic Air Surveillance Test Uses HAARP to Detect Aircraft Beyond Alaska Radar Coverage

An Alaskan Command (ALCOM) experiment detected aircraft beyond the coverage of Alaska’s long-range radars by pairing the High Frequency Active Auroral Research Program (HAARP) transmitter at Gakona with a low-cost, 16-element receiving array at Cold Bay, the Department of War said on October 20, 2026. The live-fly campaign, run from September 7 to 11, 2026, closed out a three-year Arctic air domain awareness experiment series aimed at closing air surveillance gaps across Alaska.

The test comes as Washington and Ottawa work to modernize sensors on the northern approaches. Alaska’s air picture still rests on the Alaska Radar System, 15 AN/FPS-117 long-range radar sites, most of them minimally attended, from Point Barrow to Cold Bay whose line-of-sight coverage cannot see below the radar horizon over the Gulf of Alaska and the Bering Sea. Russian military aircraft operated in the Alaskan Air Defense Identification Zone (ADIZ) on February 19 and March 4, 2026, and in June 2026 Canada signed a C$2.5 billion procurement for an Arctic Over-the-Horizon Radar (A-OTHR), part of a program valued at more than C$6 billion.

How the Arctic Air Surveillance Experiment Used HAARP as Illuminator

The architecture is bistatic: transmitter and receiver sit at separate sites, and the receiver measures energy reflected off aircraft rather than echoes of its own pulses. ALCOM describes the method as bistatic over-the-horizon detection and reports full skywave detections, meaning signals refracted by the ionosphere reached aircraft beyond the curvature of the Earth.

The transmitter is the Ionospheric Research Instrument (IRI), HAARP’s main array. Publicly available specifications indicate the IRI comprises 180 crossed-dipole antennas spread across 33 acres, radiating up to 3.6 megawatts at frequencies selectable between 2.8 and 10 MHz. As a phased array, the IRI can steer and shape its beam electronically, a feature built for ionospheric research that also suits directing energy toward a surveillance area. The Air Force transferred HAARP’s operation to the University of Alaska Fairbanks on August 11, 2015.

The receive side is the new element. MITRE designed the low-cost receiver system behind the Cold Bay array and designed and executed the field experiment across the three-year series. Based on the sites’ public coordinates, Gakona and Cold Bay sit roughly 1,280 km apart, a separation that forces the signal path through the ionosphere. Cold Bay already hosts one of the Alaska Radar System’s sites, illustrating how receive nodes could share existing remote infrastructure.

ALCOM has not disclosed operating frequencies, waveform, detection ranges, track accuracy or the receiver array’s unit cost.

Truth Data From E-3 Sentry, HC-130J and KC-135 Flights

Participating aircraft included an E-3 Sentry airborne warning and control system (AWACS) aircraft, HC-130J Combat King II personnel recovery aircraft and KC-135 Stratotankers. All flew as cooperative targets over the Gulf of Alaska and the Bering Sea, their known positions serving as truth data against which each experimental detection was correlated.

“Understanding what this technology can do in the Arctic starts with collecting data under real operating conditions,” said Carolyn Stwertka, ALCOM chief scientist. “Working with operational units allows us to compare the experimental observations with known aircraft positions and assess where this approach could help address gaps in air surveillance.”

According to ALCOM, the team met or exceeded its test execution objectives, and initial results show beyond-visual-line-of-sight detections correlated with the targeted flights. Thorough data analysis is ongoing.

The target set defines the limits of what has been shown. The E-3, HC-130J and KC-135 are large four-engine airframes with substantial radar cross-sections and predictable flight profiles. The released results establish that the HAARP and Cold Bay pairing can detect and correlate big cooperative aircraft; they do not yet demonstrate performance against small, low-flying or non-cooperative targets such as cruise missiles. HF propagation also shifts with time of day, season and solar activity, and auroral disturbances degrade the high-latitude ionosphere. A five-day window in September captures only part of that variability.

Bistatic OTH Radar and NORAD Modernization in the Arctic

The effort brought together ALCOM, US Northern Command (USNORTHCOM), the Air Force Research Laboratory (AFRL) and Defence Research and Development Canada (DRDC). Canadian participation ties the experiment to the binational North American Aerospace Defense Command (NORAD) modernization agenda.

That agenda already includes conventional over-the-horizon radar. On June 22, 2026, Ottawa and Canberra signed agreements for Canada’s A-OTHR, built on Australia’s Jindalee Operational Radar Network (JORN), with BAE Systems Australia as industry partner, delivery set to begin on July 1, 2026, and initial operational capability targeted for December 2029. BAE Systems says the technology can detect objects thousands of kilometers away. The Department of the Air Force, for its part, opened an environmental impact statement in April 2025 covering candidate homeland OTH radar sites in Idaho, Nevada and Oregon. Canada’s June 2022 NORAD modernization plan pledged two OTH systems, an Arctic Over-the-Horizon Radar and a Polar Over-the-Horizon Radar; polar coverage is the hardest case for skywave radar because auroral activity disturbs the high-latitude ionosphere, which gives Alaska-gathered data direct relevance.

JORN-class systems rely on purpose-built transmit and receive sites, with receive arrays kilometers long. The ALCOM experiment tests a different proposition: whether an existing high-power transmitter can feed compact receivers at remote locations. In Alaska, where vast distances, harsh weather and limited infrastructure complicate air surveillance, cheaper receive nodes would reduce the logistics cost of extending coverage.

Analysis: The experiment’s value lies less in the transmitter than in the receiver economics. HAARP is a university-operated research facility, an unlikely candidate for a 24/7 operational sensor. What ALCOM and MITRE have tested is a pattern: low-cost HF receive nodes at existing remote sites, exploiting a powerful illuminator to watch maritime approaches that fixed AN/FPS-117 radars cannot see. If analysis holds against non-cooperative targets, that pattern could bridge today’s Alaska Radar System and an OTH architecture that will not reach initial capability before late 2029.

ALCOM has not announced a follow-on phase, a transition sponsor or a program of record. The next marker is the completed data analysis, which should quantify detection range, track accuracy and false-alarm rates. Open questions include winter and auroral performance, results against small low-altitude targets, and whether the receiver concept could pair with transmitters other than HAARP.