There are a few places around the world where military pilots go when they want to train for low-level passes over difficult terrain, and few among them are as legendary as the UK’s Mach Loop. The Mach Loop, also called LFA-7 in North West Wales, has become a common spot for aviation enthusiasts to capture incredible images of low-flying fighter jets and helicopters as they often attack the training area one at a time, dashing through the canyons at altitudes as low as 250 feet. Each and every opportunity one gets to see an F-15 flying through a canyon from above is special, but every so often, something truly unusual make a pass through the Mach Loop: like not one, but four U.S. Special Operations MC-130Js flying in a low-level tactical formation through the legendary canyons.

These U.S. Air Force MC-130J Commando IIs were purpose-built by Lockheed Martin with the special operations community in mind. Built to serve as troop and equipment transports or refuelers, these aircraft come with more powerful engines than their predecessors and the ability to land and take off in austere environments — even ones with no legitimate airfield to speak of. Like the U.S. Army’s 160th Special Operations Aviation Regiment (SOAR), Air Force special operations pilots must be able to fly in all sorts of difficult conditions, including under cover of darkness and at extremely low altitude — where many modern anti-aircraft radar systems won’t detect them — making training flights in places like the Mach Loop extremely valuable.

In fact, in the coming years, every special operations MC-130J will be equipped with the Raytheon AN/APQ-187 Silent Knight terrain-following/terrain avoidance radar system that will allow the aircraft to follow the terrain closely while limiting the likelihood of a collision. This sort of technology has been around for some time, as the B-1B Lancer was long relied on ground-avoidance radar to allow it to enter enemy territory beneath detection but has thus far not become a common facet of America’s special operations aircraft.