Requirements for Rotating Beacons at Airports
Airport Rotating Beacons
Airport rotating beacons must meet the specifications of AC 150/5345-12.
All airport rotating beacons project a beam of light in two directions, 180 degrees apart. For civil land fields only, the optical system consists of one green lens and one clear lens.
The rotating mechanism rotates the beacon to produce alternate clear and green flashes of light with a flash rate of 24-30 flashes per minute.
The main purpose of the beacon is to indicate the location of a lighted airport, and a rotating beacon is an integral part of an airfield lighting system.
6.1.4.1 L-802A Beacon. The L-802A rotating beacon is the standard high intensity rotating beacon and is installed at all airports where high intensity lighting systems are used. See Figure A-68 for a typical beacon.
6.1.4.2 L-801A Beacon. The L-801A rotating beacon is the standard medium intensity beacon and is installed at airports where only medium intensity lighting systems are used, unless special justification exists requiring the use of a high intensity beacon at the site. Such a justification includes high background brightness caused by neighboring lights, or where the beacon is used as a navigational aid rather than for location and identification.
6.2 System Design
Power Supply
Primary power supply for airport rotating beacons is either from an existing 120/240-volt AC power supply or from a separately located
distribution transformer.
Match, as closely as possible, the primary circuit wire size to the lamp’s rated voltage. See Figure A-69 for formulae to calculate wire size and
voltage drop.
Where the separation distance between power supply and the beacon is excessive, booster transformers are recommended to maintain proper
voltage at lamp receptacles.
Control Circuits
Airport rotating beacons employ simple switching circuits to energize and de-energize the power supply. The control system design varies.
At a small airport, all control equipment and circuitry is self-contained in the power supply equipment; at a large airport, a complex control system
is needed. The two types of control systems used are direct control or remote control:
Direct Control
Direct control systems are controlled at the power supply through a switch that energizes the branch circuit supplying the power to the airport beacon.
Normally, this type of system is used for the control of rotating beacons at small airports and for other miscellaneous associated lighting circuits.
Automatic control of the beacon is obtained through a photoelectric switch with a built-in method of switching from automatic to manual control.
See Figure A-70 for a typical automatic control.
Remote Control
Remote control systems are controlled from a remote-control panel that may be located in the cab of the control tower or at other remote areas, using a control panel per AC 150/5345-3.
This panel contains switches and other devices that control operating relays in the vault from which the power is supplied through the relay
contacts to the lighting visual aid.
The following control voltages are used for remote control of equipment.
See Figure A-71.
120-Volt AC.
Where the distance between the remote-control panel and the vault is not great enough to cause an excessive voltage drop in the control
leads, use the standard control panel switches to operate the equipment power supply relays directly.
Use No. 12 AWG control cable to connect the control panel to the power components in the vault.
Use the formula in Figure A-69 to calculate the maximum permissible separation between control point and vault, using the manufacturer’s
electrical operating circuit.
In many cases, 120-volt AC, special low-burden auxiliary relays, and having the proper coil resistance, may be more advantageous for expanding the existing 120-volt AC control system than redesigning the control system to 48-volt DC.
48 Volt DC.
Use a low voltage 48-volt DC control system where the distance between the control panel and the vault would cause an excessive
voltage drop with a 120-volt AC control system.
In this system, the remote-control panel switches that, in turn, control the miscellaneous lighting circuits activate sensitive pilot relays.
The DC control system is adequate for up to 7,900 ft (2,408 m) separation.
Duct and Conduit System
For an underground power supply, install cable runs in ducts or conduits in areas that are to be stabilized or surfaced.
Install cable runs to the top of towers in conduit. This provides ready access for maintenance, modification of circuits, and protection to cables
during repairs of surface or stabilized areas.
Provide a reasonable number of spare ducts or conduits in each underground bank for maintenance and future expansion of facilities.
Avoid routing underground duct or conduit through areas that may have to be excavated. Ensure that all duct and conduit dimensions meet national,
state, and local electrical codes.
6.3 Installing a Rotating Beacon
Mounting The Beacon
Mount all airport rotating beacons higher than any surrounding obstructions so that the bottom edge of the beacon’s light beam, when
adjusted correctly, will clear all obstructions.
Beacons may be mounted on the roof of hangars or other buildings; on top of control towers when authorized by the local FAA regional office, or on wooden power pole towers and metal towers.
Check the mounting for the beacon support legs with the appropriate space and dimensions per the beacon manufacturer’s recommendations.
Hoisting and Securing
Prior to hoisting the beacon, review the manufacturer’s assembly drawings of the beacon.
Where it is impractical to hoist the assembly in one piece, disassemble the beacon into parts following the manufacturer’s recommendations.
Ensure the mounting platform at the top of the tower has the correct bolt pattern from the manufacturer’s installation drawings.
Hoist the beacon into place by means of a sling, taking care not to chafe any surface of the assembly.
Once in place, secure the base of the beacon to the mounting platform and reassemble per the manufacturer’s instructions.
Leveling. Level the beacon following the manufacturer’s instructions.
Servicing. Before placing the beacon in operation, check the manufacturer’s manual for proper servicing requirements (including any beam adjustments). Follow the manufacturer’s servicing requirements for each size beacon.
6.4 Maintenance
Maintenance must be performed per AC 150/5340-26.
6.5 Beacon Towers
Typical beacon towers are per Figure A-72, Figure A-73, and Figure A-74.
Location.
150/5300-13 contains the standards for locating beacon towers.
The FAA may recommend obstruction lights on beacon towers that are less than 200 ft (61 meters) above ground level or Title 14 CFR Part 77,
Objects Affecting Navigable Airspace, standards because of a particularly sensitive location.
Ensure that all requirements in AC 70/7460-1, Obstruction Marking and Lighting, are met before erecting any structure that may affect the National Airspace System (NAS).
Description of Towers
Structural Steel Towers.
Towers must conform to AC 150/5370-10 and consist of structural steel parts for the basic tower.
Standard tower heights are 51, 62, 75, 91, 108, 129, and 152 ft (15.5, 19, 23, 28, 33, 39, and 46 meters, respectively).
Each tower is supplied with a telescoping ladder and a mounting platform for a high intensity beacon, approximately 7 ft square (0.65 meters square) with rails and grating.
The railings are punched to permit mounting of a “T” cabinet on any inner surface.
See Figure A-72 for typical 51-foot (15.5 m) tower installations.
Tubular Steel Towers.
6.5.2.2.1 Towers consist of different lengths of low alloy, high strength tubular steel sections with 60,000 PSI yield strength, welded together to obtain a basic tower height of 51 ft (15.5 m).
6.5.2.2.2 At the top of the tower is a platform (welded) to accommodate a high intensity beacon, and a safety device consisting of a cable, locking clip, and belt combination, that permits a workman to climb the tower and to secure himself in the event of a misstep.
6.5.2.2.3 Check with the airport beacon manufacturer to ensure the best tower design is selected for the model of beacon purchased. Be prepared to
supply local wind velocity and ice load data to the tower manufacturer. See Figure A-73.
Prefabricated Tower Structure.
Prefabricated tower structure components consist of two lower sections fabricated in 20-foot (6 m) lengths with one 11-foot (3.5 m) upper section
and an 8-foot (2.4 m) diameter service platform with rails and caging for mounting a beacon, and a steel rung ladder for entrance to the platform.
See Figure A-75.
Tip-Down Pole Towers.
6.5.2.4.1 These towers consist of a two-section octagonal tapered structure with a
counterweight and hinge.
6.5.2.4.2 The top section/counterweight is attached to the bottom section using a
hinge that rotates upon a 1 1/4-inch diameter stainless steel rod.
6.5.2.4.3 The top section can easily be raised and lowered by one person using an
internal hand-operated winch.
6.5.2.4.4 Pole lengths to 55 ft (17 m) are available.
6.5.2.4.5 Check with the beacon manufacturer about the proper model of beacon to
use with this type of tower. Be prepared to supply local wind velocity and
ice loading data to the tower manufacturer.
Note: A fall protection device must be installed on all ladders per OSHA
requirements.
Beacon Pole Installation
Clearing and Grading.
6.5.3.1.1 Clear and level the site where the beacon tower is to be erected. Remove all trees and brush from the area within 25 ft (7.6 m) from the tower or as specified in the job plans.
6.5.3.1.2 Remove tree stumps to a depth of 18 inches (0.5 m) below finished grade, then fill the excavation with dirt and tamp.
.5.3.1.3 If a transformer vault or other structure is included as part of the installation, clear the area within 25 ft (7.6 m) from these structures.
6.5.3.1.4 Level the ground near the tower to permit the operation of mowing machines. Extend the leveling at least 2 ft (0.6 m) outside the tower legs.
6.5.3.1.5 Dispose of all debris from the tower site per federal, state, or local regulations.
Excavation and Fill.
6.5.3.2.1 Carry the excavation for the tower footing to a minimum of 4 inches (100 mm) below the footing depth.
6.5.3.2.2 Then backfill the excess excavation below the footing depth with gravel or crushed stone and compact to the required level.
6.5.3.2.3 Install the footing plates and then place a thickness of not less than 18 inches (0.5 m) of the same gravel or crushed stone immediately above the footing plates in layers of not over 6 inches (152 mm).
6.5.3.2.4 Thoroughly tamp in place each layer above the footing plates.
6.5.3.2.5 The remainder of the backfill may be of excavated earth placed in layers not to exceed 6 inches (152 mm).
6.5.3.2.6 Thoroughly compact each layer by tamping.
6.5.3.2.7 Where solid rock is encountered:
Cut the tower anchor posts off at the required length and install the hold down bolts as indicated in the plans.
Anchor each tower leg to the rock with two 7/8-inch (22 mm) diameter by 3-foot (0.9 m) long expansion or split hold down bolts and then grout each bolt into holes drilled into the natural rock with neat Portland cement.
Except as required for rock foundations, do not cut off or shorten the footing members.
If the excavated material is not readily compacted when backfilled, use concrete or other suitable material.
Install the concrete footing for tubular towers per the manufacturer’s recommendations.
Footing height does not include the footing portions located in the topsoil layer.
Wind Cones.
General.
6.6.1.1 This section covers the installation of two types of wind cones: L-806 (supplemental wind cone) and L-807 (primary wind cone).
6.6.1.2 Title 14 CFR Part 139 requires that an airport must have a wind cone that visually provides surface wind direction information to pilots.
6.6.1.3 If a primary wind cone is not visible to pilots on approach and takeoff at each runway end, supplemental wind cone(s) must be provided.
6.6.1.4 If the airport is open for air carrier operations at night, the wind cones (both primary and supplemental) must be lit.
6.6.1.5 The guidance in this AC is recommended for all applications involving wind cones.
Discussion.
The primary wind cone is needed at any airport without a 24-hour ATCT. At an airport certificated per Title 14 CFR Part 139 a primary wind cone is required whether the ATCT is full-time or part-time.
6.6.2.1 The source of airport wind information reported to pilots may be 2 to 3 miles (3.2 to 4.8 km) from the approach end of a runway.
6.6.2.2 Factors such as topography, approaching fronts or thunderstorms could result in much different wind conditions near runway ends than those
reported to pilots from the primary wind information source.
6.6.2.3 Supplemental wind cones may be useful to provide pilots a continuing visual indication of wind conditions near the runway ends during landing and takeoff operations.