AFRL lights the way to remote airfields with portable LED-based runway lighting

  • Published
  • By John Schutte
  • Human Effectiveness Directorate
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Even in the most dangerous military air operations involving covert blacked-out conditions on hostile airfields, pilots need critical visual indicators to safely guide them. Researchers at the Air Force Research Laboratory's Human Effectiveness Directorate want to light the way for these pilots who often must ease heavy cargo aircraft onto remote, austere runways. 

Working with Optical Research Associates of Pasadena, Calif., under a Small Business Innovative Research (SBIR) grant, engineers have designed and developed a portable, covert airfield lighting system (PCALS) based on light emitting diode (LED) technology rather than conventional incandescent bulbs. 

The dual-mode runway edge lights can be activated in a visible light mode or switched to an infrared mode visible only through night vision equipment, according to Dr. Peter L. Marasco, an electrical-optical engineer with AFRL/HE's Warfighter Interface Division, Battlespace Visualization Branch (HECV). 

The covert mode would guide heavy military cargo aircraft into austere environments such as Afghanistan and Iraq where quickly established runways may be short, unpaved and in hostile territory. 

The difference between covert and visible mode is basically the wavelength of light that the LEDS are emitting, Dr. Marasco said. 

The project began in 2004 when the Air Force Electronic Systems Center (ESC) at Hanscom Air Force Base, Mass., sought a testbed runway lighting system to help explore the feasibility of deploying portable covert lights with a GPS-based aircraft landing system, Marasco said. Part of ESC's mission is providing the latest command-and-control systems technology for the United States military. 

The only portable runway lighting in the Air Force inventory then was an Emergency Airfield Lighting System (EALS) developed as a stop-gap system for conventional airbases during extended power outages, said Ms. Sharon A. Dixon, an HECV human factors psychologist who conducted a human factors and usability assessment of the PCALS system. 

Resourceful warfighters in the field improvised to meet an immediate need for lights on austere airfields or "air bases in places that were not meant to have air bases," as Marasco describes the bulldozed dirt airstrips onto which they installed EALS systems. 

"They were putting EALS to use for far longer than it was designed to be used, so affordability and maintainability became an issue," said Marasco, technical lead for the SBIR Phase 1 effort. 

"The EALS wasn't particularly portable since it had to be trucked out on a 48-foot flatbed trailer," added Ms. Dixon. 

The EALS system uses costly incandescent light bulbs with an expected lifespan of only a few hundred hours and it is powered by a 30-kilowatt generator. For aerial shipping it needs three of the five available 7-feet by 9-feet pallet spaces on a C-130. 

In contrast, PCALS has a lightweight four-kilowatt generator, an LED's lifetime can range to 100,000 hours, and a well-packaged production version will need only one C-130 pallet, Ms. Dixon said. 

Dr. Marasco noted that ESC's requirements and an evolving LED technology crossed paths at an opportune moment. 

"It was an interesting conjunction of idea and technology. The LED industry was going through a revolution in technology," Dr. Marasco said, "When all was said and done, LED turned out to be the most viable technology available. It seemed like every 18 months LEDs were doubling in intensity and power." 

Engineers leveraged LED advances to design a system that is much smaller, lighter, more portable and less power-hungry than other currently available portable lighting systems, Dr. Marasco said. 

PCALS was successfully demonstrated at the 2005 Team Patriot military mobility exercises at an austere, 5000-feet unimproved airstrip and the paved 10,000-feet Volk Field Air National Guard Base in Wisconsin. 

PCALS was observed by both a C-130 special operations Air National Guard unit that flew five approaches to the covert lighting using night-vision goggles at the unimproved airstrip, and a UH-1 Huey Army National Guard unit at both the unimproved and paved airfields. Pilots from both aircraft reported seeing the runway lights about 25 miles out and indicated they would have seen them from farther out if not for local cultural lighting, Ms. Dixon said. 

Feedback from these field tests also indicated that PCALS is easy to roll out, set up and implement in the field. 

To help transition the lights to civilian airfields, Marasco said engineers designed the visible mode to comply with the Federal Aviation Administration's medium-intensity visible light requirements, which is the FAA guideline for visible lighting at a commercial runway. 

A commercial airfield in Tampa, Fla. has purchased the blue, omni-directional taxiway lights that operate in visible mode only and can be seen primarily from the ground. The lights--designed and manufactured by Cooper Crouse-Hinds under subcontract to Optical Research Associates--are less costly for commercial airports to operate and maintain, Dr. Marasco said. 

The Department of Defense SBIR program provides funding--a total of about $1.14 billion in 2007--for early-stage research and development projects involving small technology companies, according to the DoD SBIR website. The projects must be directed at meeting a DoD need and also have commercial applications. 

The PCALS technology will be exhibited at the Air Force Association's 2007 Air & Space Conference and Technology Exposition to be held September 24-26 at the Marriott Wardman Park Hotel in Washington, D. C.