Lighting Remote Airfields: A Passive Approach

Because New Mexico’s state-owned airports are in remote locations without convenient electrical service, the State Aviation Division looked for a lighting system for runways and taxiways which would not require connection to electric service. Our goal was to find a system which would have a relatively low initial cost, be reliable under all of New Mexico’s adverse weather conditions, require minimal maintenance, would meet with FAA requirements for approval, and which would not require a regular power connection. We found that passive reflector systems meet these criteria.

The passive systems are generally called "retro-reflective," because they are constructed of elements covered with a highly reflective material, that has the ability to reflect light back to its source. In the case of runway lighting, the light source is the airplane’s landing light, which is reflected back to the pilot when a mile or more out. In fact, reports of "good" runway lighting have been received where the pilot claims to have seen the runway lighting at over five miles out! While we are all familiar with the brightness of the modern highway signage at night, this airport retro-reflective material is much more reflective. It is made of a tough, weather resistant plastic film covering the actual reflective surface. The reflective surface itself is a miracle of modern science, and is able to reflect light over wide angles of incidence. The material can handle rain, snow, hail, blowing sand, and can easily tolerate New Mexico’s high summer temperatures, as well as its harsh winter conditions. The reflectors require little, if any, maintenance and are easily replaced if damaged by mowing equipment or airport vehicles.

While there are several manufacturers of retro-reflective systems, the State of New Mexico has specified the system manufactured by Reginald Bennett International, Inc. (RBI) of Ajax, Ontario, Canada, for the four state-owned airports cited below. We are not alone in approving this product. It has been adopted for use by the Canadian Armed Forces as a portable system they can utilize anywhere. In addition to runway and taxiway markers, RBI also produces reflectors for heliports, and a passive approach slope indicator system.

The runway markers are constructed of sturdy aluminum plate over which the reflective material and its protective cover are bonded. The color of the protective cover determines the reflected color, so the material can be used for a variety of purposes. For example, the runway markers are green from the approach side and red on the runway side to indicate the end of runway braking area. RBI’s helicopter pad reflectors are generally yellow, as approved by the FAA and ICAO. All markers are mounted to the ground on frangible (breakaway) mounts, able to withstand winds up to 125 mph.

The State of New Mexico has installed retro-reflective lighting at all of the state-owned airports (Conchas Dam, Tatum, Eunice, and Navajo Lake.) We have found general approval from the pilots who have commented on it. Additionally, reflective systems have been installed at Magdalena, Logan, and other airports, even some with electric power to the field. In the installations at the state-owned airports, we have combined retro-reflective runway and taxiway lighting with solar recharged battery powered stroboscopic approach lights. We feel that this is a good use of battery powered lighting. If something should happen to a strobe or to the power pack itself, only the strobe will be lost—the passive runway reflectors will not be affected.

The strobe system, which RBI has also provided to the State of New Mexico, is a radio-controlled, three-light system which can be activated and seen from a distance of at least eight nautical miles. Depending on the space available from the runway end to the airport property line, the system’s three strobes are placed in a straight line, or in a triangle. The preferred configuration is a straight line ahead of the runway threshold and extending the runway centerline, with two hundred feet between each light. These lights flash at sixty times per minute and in sequence, to act as an approach path indicator. If space does not permit this configuration, then two strobes are placed at the runway threshold, and one is placed on the extended runway centerline away from the threshold. These lights can be flashed simultaneously or alternately, with the single light flashing, then the two threshold lights flashing to help provide approach orientation. Strobes are set to flash for fifteen minutes, then automatically shut off. The battery powering the strobes has a storage reserve of thirty-four hours before needing recharge, but the solar collector recharge unit attached to it can provide battery recharge even on cloudy days.

These passive lighting systems are proving to be an effective, reliable, and low cost means of lighting airport runways and taxiways in rural New Mexico.