Two new Leonardo AW139 helicopters specially configured to measure and map radiation levels from the air recently joined the Department of Energy’s fleet. The AW139s will replace a pair of aging Bell 412s that have been used for years in this role, which includes being on call to collect vital data after a nuclear attack or accident. The mission set also involves conducting surveys ahead of major public events, from presidential inaugurations to Super Bowls. The blue and silver ‘twin Hueys’ with their podded instruments are one of the aircraft we have gotten asked about the most over the years as their low-level search patterns over major population centers definitely garners interest wherever they operate.
The Department of Energy’s AW139s touched down at Joint Base Andrews just outside of Washington, D.C. last week. This is the culmination of an effort to replace the Bell 412s, which have been in service for more than three decades, that dates back to 2016. The new helicopters are now part of the larger Aerial Measuring System (AMS) fleet, which will be overseen by the National Nuclear Security Administration’s (NNSA) Nuclear Emergency Support Team (NEST). Historically, one AMS helicopter has been based at Andrews and the other at Nellis Air Force Base in Nevada to help better position them to respond to nuclear incidents on either side of the country.
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“The data provided by AMS [Aerial Measuring System] aircraft are often the first readings that federal, state, local, territorial, and tribal officials can use to make vital health and safety decisions,” Kasia Mendelsohn, acting Associate Administrator for NNSA’s Office of Counterterrorism and Counterproliferation, said in a statement after the arrival of the AW139s. “These new helicopters will increase NEST’s ability to conduct a wide range of national security and public safety missions.”
The current AMS fleet also includes three specially modified Beechcraft King Air 350ER twin-engine turboprops, which replaced old King Air types back in 2019. These aircraft are configured primarily to spot and geolocate radioactive hotspots down below, as well as collect details about that radiation, which much lower-flying AMS helicopters would then survey more closely. AMS’ fixed and rotary wing components are both able to generate valuable data in near-real time, along with gathering information that personnel on the ground can analyze further after the completion of a sortie.
As already noted, the entire AMS is on call to be able to help spot and track the spread of radiation following any attack involving nuclear weapons, as well as so-called “dirty bombs,” which use conventional explosives to disperse radioactive material. The Department of Energy aircraft can also help with the response to nuclear accidents.
In addition, the AMS helicopters fly survey missions ahead of major domestic events, as well as other routine sorties over major cities, to help establish baseline radiation levels. Having a picture of what normal, naturally occurring radiation readings are for a specific area makes it easier to identify concerning abnormalities.
Just today, NNSA announced that one of the AMS Bell 412s will be conducting baseline collection sorties over Milwaukee, Wisconsin between July 9 and 11. Milwaukee will host the 2024 Republican National Convention next week ahead of this year’s presidential election, which a large number of prominent politicians and other dignitaries, including former president Donald Trump, are set to attend.
The AW139s offer important improvements over their predecessors for these critical missions. The new AMS helicopters can cruise at around 190 miles per hour and have a maximum range of 650 miles, according to NNSA. Their fuel capacity also means they can stay aloft for nearly three and a half hours during survey missions within a more limited area. For comparison, the existing Bell 412s configured for this mission have a range of just 250 miles and an endurance of around one and a half hours.
“The flight time of the AW139 greatly improves the efficiency of an aerial survey and decreases the time needed to provide survey results to incident managers,” NNSA has said in the past.
The AW139s have greater overall payload capacities. The new helicopters can therefore carry all of their sensors and other mission systems internally, rather than in external pods as is the case with the existing Bell 412s.
Furthmore, “the new helicopter includes state-of-the-art integrated avionics and fully digital glass cockpit to minimize pilot workload and improve situational awareness,” per NNSA. “Communications equipment will enable the pilots and crew to communicate with operations on the ground such as NEST’s Radiological Assistance Program and police, fire, and emergency services. A satellite communication system provides both data and voice capability to ensure real-time measurements are transmitted back to DOE’s national laboratories for interpretation and faster product delivery to an incident commander.”
The AW139 has a digital ‘backbone’ that NNSA says will more readily allow for the integration of new and improved capabilities down the road, too, “such as forward looking infrared or other thermal imaging cameras, or video and still images to enhance aerial survey interpretation products.”
Originally developed as part of a partnership between Italy’s Agusta and Bell, the AW139 is a popular in-production design in current service with armed forces, law enforcement organizations, other first responders, and commercial operators around the world. The U.S. Air Force is currently in the process of replacing a portion of its aging UH-1Ns, a militarized variant of the Bell 212 that preceded the 412 model, with MH-139 Grey Wolves, a version of the AW139 created for that service in cooperation with Boeing. Earlier this year, it emerged that the Air Force was slashing expected MH-139 purchases in half.
There are robust supply chains for the AW139s in the United States, with the new AMS-configured helicopters coming from the same Philadelphia, Pennsylvania plant as the Air Force’s MH-139s. That facility also assembles examples for other customers.
NNSA says it will now take around six weeks before its new AW139s are fully ready to fly real AMS missions “as the flight crews familiarize themselves with the configuration of the controls, conduct a thorough validation of their scientific equipment, and calibrate the detectors.”
The delivery of the two AW139s last week already marked an important milestone in modernizing the AMS, a key capability for keeping an eye out for potential nuclear attacks or other incidents and responding to any crises or contingencies involving the spread of radiation that might arise.
Contact the author: joe@twz.com