AIM
5/19/22
wire span. The lights are beamed towards the
companion structure and identify the area of the wire
span.
d.
High intensity flashing white lights are also
employed to identify tall structures, such as chimneys
and towers, as obstructions to air navigation. The
lights provide a 360 degree coverage about the
structure at 40 flashes per minute and consist of from
one to seven levels of lights depending upon the
height of the structure. Where more than one level is
used the vertical banks flash simultaneously.
2
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2
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4. LED Lighting Systems
Certain light
−
emitting diode (LED) lighting systems
fall outside the combined visible and near
−
infrared
spectrum of night vision goggles (NVGs) and thus
will not be visible to a flightcrew using NVGs.
The FAA changed specifications for LED
−
based red
obstruction lights to make them visible to pilots using
certain NVG systems, however, other colors may not
be visible.
It is recommended that air carriers/operators
—including Part 91 operators—who use NVGs
incorporate procedures into manuals and/or standard
operating procedures (SOPs) requiring periodic,
unaided scanning when operating at low altitudes and
when performing a reconnaissance of landing areas.
2
−
2
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2
Air Navigation and Obstruction Lighting