U-2 Cold War spy plane causes air traffic control to crash, grounds hundreds of planes

Last week, a 1950s Cold War spy plane — the Lockheed U-2 Dragon Lady — caused hundreds of planes across the US to be grounded for an hour, and delaying hundreds more that were already airborne. The U-2, which was just minding its own business at an altitude of 60,000 feet above southern California, triggered a software bug that caused the FAA’s air traffic control system to “overload” and shut down. The backup system also failed, presumably for similar reasons. The beautiful irony is that both the plane and the air traffic control software were created by Lockheed. How did an ancient plane that has been trawling the skies for almost 60 years cause such a catastrophic failure?

The U-2 Dragon Lady, so called after the plane’s original CIA code name, was originally conceived in the early ’50s as an ultra-high altitude reconnaissance aircraft that could evade the Soviet Union’s air defenses. It was believed back then that Soviet radar maxed out at an altitude of 65,000 feet (12 miles, 20 kilometers) — and so the U-2 was designed to have a service altitude of 70,000 feet or higher. Much to the US and UK’s dismay, it would eventually come to light that the Soviets had improved their radar considerably, and could reliably detect overflights made by the U-2. By 1957, after just a couple of years of operation, the single-seat, single-engine U-2 had enjoyed unprecedented success as a spy plane, photographing around 15% of the Soviet Union. It wouldn’t be until 1960 that the Soviets finally managed to shoot a U-2 out of the sky using an SA-2 surface-to-air missile. (The pilot, Francis Powers, survived — but so did much of the plane, rewarding the Soviets with lots of tasty intel.)

An old-school U2 with its various loadouts

As far as armament goes, the original U-2 was mostly outfitted with a massive camera — and I really mean massive: An 180-inch (4,500mm)  f/13.85 lens with 13-inch (33cm) square format photographic film. From an altitude of 65,000 feet, the camera/film could resolve details as small as 2.5 feet (76cm). The U-2′s image quality and resolution have only really been surpassed by orbiting satellites in the last couple of decades. The modern-day U-2S can be outfitted with a range of digital sensors, allowing it to be used in both war (it saw active duty in Afghanistan and Iraq) and civilian/domestic settings. While satellites are now the reconnaissance tool of choice, airplanes like the U-2 are very useful if you need a spotter in the sky quickly and can’t wait for a satellite to maneuver. Eventually the U-2 will probably be retired completely in favor of unmanned drones like the RQ-4 Global Hawk. (Read: DARPA shows off 1.8-gigapixel surveillance drone, can spot a terrorist from 20,000 feet.)

The view from 70,000 feet out the window of a U-2 is quite spectacular

On April 30, it would seem a U-2 was just casually going about its (military) business high above southern California. Usually aircraft above 60,000 feet (FL600) are not required to communicate with air traffic control, instead operating under “visual flight rules” (they have to look out the window and make sure they don’t hit anyone else). For some reason, the air traffic control software at Los

Angeles’ Area Control Center bugged out and thought the plane was actually flying at 10,000 feet. The software, Lockheed’s ERAM (En Route Automation Modernization) then overloaded while trying to plot a safe route through the hundreds of planes currently in the skies around California.
It isn’t known why ERAM decided to crash this time, but not the dozens of other times that the U-2 has been over US skies. It’s possible that the U-2′s transponder bugged out and responded with an erroneous altitude. Or maybe ERAM, just like every other piece of software in the world, has some bugs that need to be worked out. With this being a military operation, it’s entirely possible that something slightly more interesting or nefarious was afoot — but I doubt the USAF would tell us if the U-2 was trying out a new air traffic control jamming device…