Obstruction lights are on all elevated obstructions on the airport and all other
obstructions within a given glide angle of an airport. Obstruction lighting includes
flashing beacons and steady-burning lights; both are aviation red. Some on-airport
obstruction lights are manually controlled from the tower; most obstruction lights have
automatic photoelectric switches.
Optical Landing System
Many naval air stations have an Improved Fresnel Lens Optical Landing System
(IFLOLS) installed abeam the touchdown point along the left side of a runway used for
field carrier-landing practice. The OLS provides glide slope information independent of
other visual aids; however, it does not provide centerline alignment information. The
OLS is normally turned on whenever the runway is being used. Although the shore-
based lens may differ physically from the shipboard lens, the view presented to the pilot
is the same in either case (see Figure 4-14).
The OLS consists of the following lighting components:
Source Lights Yellow line of lights referred to as the "meatball" or "ball." A red
source light is visible to the pilot when the aircraft is too low.
Datum Lights Horizontal bar of green lights that provides a visual reference for
determining the aircraft's position in relation to ideal glide path
Wave-off Lights Flashing red lights that inform the pilot to execute a missed
approach and are operated by the Landing Signal Officer (LSO) during FCLPs
Cut Lights Green lights above the source lights that are used by the LSO to
acknowledge control of a no radio (NORDO) aircraft