The FAA has issued an Information for Operators message advising operators that LED lights are significantly less visible than traditional incandescent light bulbs when viewed through Enhanced Flight Vision System (EFVS), Enhanced Vision Systems (EVS) and Night Vision Goggles (NVG).
On January 4, 2007 the U.S. Congress passed the Energy Independence and Security Act which mandates phasing out incandescent light bulb use by 2012-2014 for energy conservation purposes. As a result, incandescent light bulbs are being replaced with LED lights at various airport locations and on obstacles throughout the National Airspace System.
However, certain advanced vision systems, such as EFVS and EVS, rely on Forward Looking Infrared (FLIR), a type of thermal imaging used for vision enhancement. The ability of these devices to image LEDs is diminished due to light wave length and reduced heat signature when compared to traditional incandescent lights. As a result, LEDs are not sensed by EFVS and EVS.
NVGs primarily use light amplification for imagery. Certain LED lights fall outside the combined visible and near-infrared spectrum of NVG.
Presently, only approach lights have not been subject to the change-over. All other lighting on an airport or on obstacles could be LED or a combination of LED and incandescent lights. The FAA is working with industry, through SAE G-20 (Airport Lighting Committee), to arrive at a technology solution that would make LED and EFVS interoperable.
Operators are urged to use caution when relying on advanced vision system (EFVS, EVS or NVG) imagery. Dramatic image changes may occur when maneuvering from a surface marked with incandescent lights to a surface marked with LED lights, additionally, LED obstacle beacons may be more difficult to identify.
Frequency spectrum issues relating to NVG and LED lights are outlined in SAFO 09007.