This week, Lockheed Martin officially took delivery of a key part of the F-35 fighter’s combat functionality—the pilot’s helmet. The most expensive and complicated piece of headgear ever constructed, the F-35 Gen III Helmet Mounted Display System (HMDS) is one of the multipurpose fighter’s most critical systems, and it's essential to delivering a fully combat-ready version of the fighter to the Marine Corps, the Navy, and the Air Force. But it almost didn’t make the cut because of software problems and side effects akin to those affecting some 3D virtual reality headsets.

Built by Rockwell Collins ESA Vision Systems International (a joint venture between Rockwell Collins and the Israeli defense company Elbit Systems), the HMDS goes way beyond previous augmented reality displays embedded in pilots’ helmets. In addition to providing the navigational and targeting information typically shown in a combat aircraft’s heads-up display, the HMDS also includes aspects of virtual reality, allowing a pilot to look through the plane. Using a collection of six high-definition video and infrared cameras on the fighter’s exterior called the Distributed Aperture System (DAS), the display extends vision a full 360 degrees around the aircraft from within the cockpit. The helmet is also equipped with night vision capabilities via an infrared sensor that projects imagery inside the facemask.

The helmet is an essential part of the aircraft’s cockpit. Some pilots have called the helmet's austere touchscreen Panoramic Cockpit Display “the most naked cockpit in history“ because of its lack of switches and other physical instrumentation. (“Not true,” said Lockheed Martin F-35 Pilot Vehicle Interface lead Michael Skaff in a presentation he gave on the cockpit. “The Wright flyer had fewer switches.”) When combined with the cockpit’s built-in voice recognition capabilities, the helmet will allow the pilot to track everything in the aircraft’s sphere of visibility.

The helmet runs for about $600,000, which doesn't include software integration with the aircraft’s systems. But Lockheed Martin hopes the cost will drop as production ramps up.

Jitter bug

In 2011, Department of Defense F-35 program officials were concerned about some major problems with the second generation of the HMDS helmet. One of them was “jitter," a sensitivity in the helmet’s motion sensors that caused the symbology displayed inside the helmet’s visor to bounce when the aircraft was being buffeted by winds or experiencing vibration.

There was also a latency in the video from the DAS cameras that caused the pilots' view to slightly lag behind where their heads were pointed. As a result, pilots were suffering from motion sickness caused by the helmet display—a symptom that many users of other virtual reality systems have experienced, including in early versions of the Oculus Rift VR headset.

Another problem was the helmet’s display of night vision video. The resolution in the original sensor used in the system had 20/70 acuity—meaning the device could see things at 20 feet that a normally sighted person could see at 70 feet in daylight. Most military night vision goggles have an acuity of 20/25. That meant the night-vision features of the helmet were nearly worthless in combat situations.

In September 2011, to cover for a potential failure to deliver, the Defense Department contracted BAE systems to build a cheaper, lower-tech alternative to the HMDS. BAE’s alternate helmet used a variation on the Head Equipment Assembly, a system the company had already developed for the Eurofighter Typhoon flown by the air forces of Britain, Germany, Italy, and Spain. It uses a series of infrared LEDs on the helmet to track the pilot’s head position and projects a holographic display of aircraft data and target information within the helmet’s visor. A pair of binocular night vision goggles could be clipped onto the helmet to provide the night vision capability required.

All in

But development of the BAE option was shot down in October of 2013, when the F-35 program decided that Rockwell Collins and Elbit had solved the majority of the issues with their HMDS in its third generation. After more than 15,000 hours of flight time testing, Lockheed Martin and the DOD signed off on the Rockwell/Elbit helmet as their sole solution.

Gen III of the HMDS has an improved infrared sensor and head-tracking technology, as well as a better imaging system with a backlit internal display. Vision Systems International has delivered 160 of the helmet systems to Lockheed so far, and the helmets will be rolled into the next round of low-rate production for the aircraft.