ANTI-COLLISION LIGHTS
4-197. In formation flight, anti-collision lights are normally turned off with the exception of trail aircraft.
Operation of anti-collision lights can be a major distraction to succeeding aircraft within the flight and may
hamper safe operation. Anti-collision lights are used according to AR 95-1, Federal Aviation Administration
(FAA) directives, host country/theater directives, and appropriate SOP guidance.
LANDING LIGHT OR SEARCHLIGHT
4-198. The landing light must be used with discretion and due consideration for other aircraft and safety.
4-199. During tactical operations, the landing light is only used to prevent a hazardous situation from
developing, with due consideration of enemy threat. The unfiltered landing light can be used with NVG under
emergency/administrative conditions, but aircrews must direct their scan and the light to prevent dimming the
NVG and reducing their effectiveness.
4-200. Use of landing lights or searchlights is determined by factors such as crewmember experience and
ambient light conditions (figure 4-49). Aviators who constantly rely on it might not develop techniques to fly
without it; however, a crew striving to never use it may put the aircraft at risk. The use of the landing light may
reduce the ability to see under certain atmospheric conditions such as fog or blowing snow. Each situation must
be evaluated separately.
4-201. The use of IR searchlight/landing light during NVG aided missions is at the discretion of the aircraft
or flight lead pilot in command. For all NVG operations, aircraft are required to have an operational searchlight,
preferably with an IR filter installed. Benefits or limitations of the IR searchlight are dependent on ambient
illumination, reflectivity of the terrain, and the positioning of the output beam. As ambient illumination
decreases, the "flashlight" effect from the IR spotlight on the NVG becomes more evident. The area illuminated
by the beam of the light is brighter and the area outside of the beam appears darker on the NVG. Terrain albedo,
or reflectivity, affects the benefits of the IR light. Different types of terrain will absorb or reflect IR light to
varying degrees. Some terrain such as sand or snow may even reflect too much light and create a "washed out"
NVG intensified image. Terrain consisting of plowed fields or asphalt may absorb the IR light and appear either
dimly lit or dark with no contrast on the NVG.
4-202. The position of the light beam also affects what is perceived through the NVG. Actual positioning of
light is dependent on individual preference. However, positioning light so that its beam is pointed straight down
has proven effective for identifying objects in the landing zone (watch out for the crater effect illusion). Another
consideration when flying with multiple aircraft is to have the last aircraft use their IR light in the landing phase
to "back-light" the LZ for the flight; however, this procedure does have its drawbacks. The preceding aircrews,
which are responsible for clearing their respective aircraft into the landing zone, may have their NVG shut down
by the introduction of the IR light (incompatible light source). When flying in built-up areas (MOUT,
runway/airfield environment) with increased cultural lighting, IR light to offset the NVG "washout" should be
considered. Utilizing the light or landing light to "burn through" the excessive illumination created by the
cultural lighting, thereby allowing aircrews a better representation of the surrounding terrain, can accomplish
this.
4-203. The other major concern with use of the NVG light is the tunneling effect it has on aircrew members'
perception. Aircrew members tend to focus on the illuminated area, to the exclusion of the areas around it.
Utilization of the searchlight should be based on METT-TC. The light can be seen from a much greater distance
than it aids vision, and the increasing availability of basic IR sensors in the world may make this technique
tactically unsound, except for short, limited periods.
POSITION LIGHTS
4-204. Inappropriate use of position and navigation lights can degrade night vision and increase the possibility
of detection by an existing threat. Aircraft in formation flight can be distracted by position and navigation lights,
thereby hampering safe operation. During formation flight, with the exception of trail aircraft, position, or
navigation lights should be dimmed or turned off according to AR 95-1, FAA directives, host nation/theater
directives, and appropriate SOP guidance. Use of IR lighting should be maximized in a tactical environment.
4-205. Army RW aircraft currently possess incandescent (heat generated), light emitting diode (LED), or
electroluminescent (slime) aircraft exterior lighting. While on their normal setting, incandescent
navigation/position lights typically trigger the NVG's automatic brightness control circuitry. This causes NVG
halo, blooming, and shutdown effects. The result is that the aircrew are able to see the aircraft lights, but may
not see the aircraft or anything else surrounding the aircraft. This can result in errors in distance estimation.
4-206. NVG visual cues may be impacted by NVG image differences between port and starboard navigation
lights. For example, an unobstructed red position light can be seen at greater range than the green position light.
Therefore, the aircraft can be detected further away at different times due to the aspect-induced appearance or
disappearance of the various position lights (particularly the port side). The same is true for other external lights.
The problem is compounded when operating in close proximity to other aircraft (for example, formation or
during a rendezvous). It is also impossible to distinguish the red from the green position lights, which may make
it difficult to determine if an aircraft is approaching or departing. Aircrew members should be aware of these
potential visual cue misperceptions and continually cross-check NVG viewing with unaided vision.
