Airport Signs, Markings, and Lighting

Airport Signs

Mandatory instruction signs have a red background with a white inscription. They are used to denote an entrance to a runway or critical area, and areas where an aircraft is prohibited from entering.

Typical mandatory signs and applications are:

• Runway holding position signs
• Runway approach area holding position signs
• ILS critical area holding position signs
• No entry signs

Location signs typically have a black background with a yellow inscription and yellow border. They are used to identify where the aircraft is located.

Typical location sign applications are:

• Taxiway location signs
• Runway location signs
• Runway boundary signs (yellow background with a black graphic depicting the runway holding position marking)
• ILS critical area boundary signs (yellow background with a black graphic depicting the ILS holding position marking)

Direction signs have a yellow background with a black inscription. Each designation is accompanied by an arrow indicating the direction of the turn.

Destination signs also have a yellow background with a black inscription indicating a destination on the airport. These signs always have an arrow showing the direction to a destination. Destinations commonly shown are runways, terminals, cargo areas, and FBOs.

Information signs have a yellow background with a black inscription. These signs provide the pilot with information such as radio frequencies and noise abatement procedures.

Runway distance remaining signs have a black background with a white numeral inscription and may be installed along one or both sides of the runway. The number on the signs indicates the distance, in thousands of feet, of runway remaining.

Taxiway Markings

Enhanced taxiway centerline markings are used at larger airports to warn pilots that they are approaching a runway holding position marking. These markings consist of two parallel, yellow-dashed lines located on either side of the normal taxiway centerline beginning approximately 150' before a runway holding position marking.

Normal taxiway centerline markings are a single continuous yellow line. Ideally, the aircraft should be kept centered over this line during taxi. However, being centered on the taxiway centerline does not guarantee wingtip clearance with other aircraft or objects.

Surface-painted location signs are located on the right side of the centerline to assist the pilot in confirming the taxiway on which the aircraft is located. These markings have a black background with a yellow inscription.

Geographic position markings are located at points along low-visibility taxi routes to identify a taxiing aircraft's location during low-visibility operations. These markings consist of an outer white or black ring with a pink circle in the middle. Either a number or a number and letter are positioned in the center of the pink circle.

Surface-painted taxiway direction signs are provided when it is not possible to provide taxiway direction signs at intersections or when necessary to supplement such signs. These markings have a yellow background with a black inscription.

Edge markings help define the taxiway's edge, primarily when the taxiway edge does not correspond with the edge of the pavement. These markings typically consist of continuous double yellow lines. Dashed lines are used when the adjoining pavement is intended to be used by aircraft (e.g., ramps and run-up areas).

Shoulder markings are yellow stripes that are used where conditions exist, such as taxiway curves that may cause confusion as to which side of the edge stripe is for use by aircraft. A taxiway shoulder is not intended for use by aircraft.

Taxiway Lighting

Taxiway edge lights outline the edges of taxiways during periods of darkness or restricted visibility conditions. They are steadily burning and emit blue light.

Taxiway centerline lights are located along the taxiway centerline to facilitate ground traffic under low visibility conditions. They are steadily burning and emit green light.

Clearance bar lights consist of three yellow in-pavement lights. They are installed at some taxiway holding positions to increase the conspicuity of the holding position in low visibility conditions and periods of darkness.

Runway guard lights are installed at taxiways that provide access to an active runway and may be used in all weather conditions. They consist of elevated or in-pavement, alternately flashing yellow lights that identify the location of a runway holding position marking.

Elevated runway guard lights are called "wig-wag" lights because they blink on and off in an alternating fashion.

Stop bar lights confirm the ATC clearance to enter or cross the active runway in low visibility conditions. They consist of a row of red, unidirectional, elevated, and in-pavement lights placed at the runway holding position (runway entrance or ILS critical area). These lights may be operated automatically or controlled by ATC. Following an ATC clearance to proceed, the stop bar is turned off, and the taxiway centerline lead-on lights are turned on.

Caution: Never cross a red illuminated stop bar, even if an ATC clearance has been received.

Holding Position Markings

Runway holding position markings indicate where an aircraft is supposed to stop when approaching a runway. These markings consist of four yellow lines, two solid and two dashed, extending across the taxiway or runway width. The solid lines are always on the side where the aircraft is to hold.

Runway holding position markings may be encountered:

• On taxiways where an aircraft is supposed to stop when it does not have clearance to proceed onto the runway.
• On runways that ATC uses for land and hold short operations (LAHSO) or taxiing operations.

• On taxiways located in runway approach areas are used at some airports where a taxiway is located in an approach or departure area. ATC notifies pilots when to hold short of a runway approach or departure area (e.g., "22-APCH" sign).

Example Instructions: "Hold short of Runway 32 approach area."

Holding position markings for instrument landing system (ILS) critical areas consist of two solid yellow lines (horizontal) connected by pairs of solid lines (vertical) extending across the width of the taxiway. ATC notifies pilots when to hold short of an ILS critical area.

Holding position markings for taxiway/taxiway intersections consist of a single, yellow dashed line extending across the taxiway's width.

Hot Spots

A hot spot is a location in an airport movement area with a history or potential risk of collision or runway incursion, where pilots' and drivers' heightened attention is necessary. They are typically located at confusing taxiway and runway intersections.

Runway Markings

Chevrons are yellow markings aligned with the runway that show pavement that is unusable for landing, takeoff, and taxiing.

Demarcation bars delineate displaced runway thresholds from unusable pavement, such as blast pads, slipways, or taxiways that precede the threshold. A demarcation bar is yellow since it is not located on the runway.

Threshold bars delineate the beginning of runways when a threshold has been relocated or displaced.

Threshold markings identify the beginning of the runway that is available for landing. Runway threshold markings come in two configurations. These markings have eight stripes of uniform dimensions, or the number of stripes is related to the runway width. Visual runways, those without an instrument approach, do not have threshold markings.

Designation markings are numbers and letters that identify a runway. The number is determined from the approach direction. It is based on the magnetic heading of the runway centerline. The letters differentiate between left (L), right (R), or center (C) parallel runways, as applicable.

Centerline markings identify the center of the runway and provide alignment guidance to aircraft during takeoff and landing. The stripes are 120' in length with 80' gaps.

Side stripe markings consist of continuous white stripes on each side of the runway. They provide a visual contrast between the runway pavement and the ground.

Shoulder markings consist of continuous yellow stripes, which are used when needed to identify pavement next to the runway that is not intended for aircraft use.

Touchdown zone markings identify the touchdown zone for aircraft on a precision instrument approach. The markings consist of groups of one, two, and three rectangular bars symmetrically arranged in pairs about the runway centerline. They are spaced in 500' increments, measured from the beginning of the runway.

Aiming point markings serve as a visual aiming point for a landing aircraft. These two rectangular markings consist of a broad white stripe located on each side of the runway centerline and approximately 1,000' from the landing threshold. Depending on the runway length, the markings are 100' to 150' in length.

Runway Lighting

Runway end identifier lights (REIL) are flashing lights that provide rapid and positive identification of the end of a runway. The system consists of two synchronized flashing lights, uni-directional or omni-directional, one on each side of the runway landing threshold.

Runway threshold lights mark both ends of the runway. They emit red light toward the runway to indicate the end of the runway to a departing aircraft and emit green outward from the runway end to indicate the threshold to landing aircraft.

Runway edge lights outline the edges of runways during periods of darkness or restricted visibility conditions. They are white, except on instrument runways where yellow replaces white on the last 2,000' or half the runway length, whichever is less, to form a caution zone for landings.

Runway edge light systems are classified according to the intensity or brightness they are capable of producing: high-intensity runway lights (HIRL), medium-intensity runway lights (MIRL), and low-intensity runway lights (LIRL). The HIRL and MIRL systems have variable intensity controls, whereas the LIRL's normally have one intensity setting.

Runway centerline light systems (RCLS) are installed on some precision approach runways to facilitate landing under adverse visibility conditions. They are located along the runway centerline and are spaced at 50-foot intervals. When viewed from the landing threshold, the runway centerline lights are white until the last 3,000' of the runway. The white lights begin to alternate with red for the next 2,000', and for the last 1,000' of the runway, all centerline lights are red.

Touchdown zone lights (TDZL) are installed on some precision approach runways to indicate the touchdown zone when landing under adverse visibility conditions. They consist of two rows of transverse light bars disposed symmetrically about the runway centerline. The system consists of steady-burning white lights that start 100' beyond the landing threshold and extend to 3,000' beyond the landing threshold or to the midpoint of the runway, whichever is less.

Taxiway centerline lead-off lights provide visual guidance to pilots exiting the runway. They alternate green and yellow from the runway centerline to the runway holding position or the ILS critical area, as appropriate.

Taxiway centerline lead-on lights provide visual guidance to pilots entering the runway and warn them that they are within the runway environment or ILS critical area. They alternate green and yellow. The fixtures are bidirectional (one side emits light for the lead-on function while the other side emits light for the lead-off function).

Land and hold short lights indicate the hold short point on certain runways that are approved for land and hold short operations (LAHSO). They consist of a row of pulsing white lights installed across the runway at the hold short point. Where installed, the lights are on when LAHSO is in effect.

Other Airport Markings

Vehicle roadway markings define a pathway for vehicle operations on or across areas that are also intended for aircraft. Zipper markings delineate the edges of the vehicle roadway. Instead of dashed lines, solid white lines may be used.

VOR checkpoint markings allow the pilot to check aircraft instruments with NAVAID signals. It consists of a painted circle with an arrow in the middle that is aligned in the direction of the checkpoint azimuth.

Nonmovement area boundary markings delineate the movement area, an area controlled by ATC. These markings consist of two yellow lines, one solid and one dashed. The solid line is located on the nonmovement area side (not under ATC control). The dashed yellow line is located on the movement area side (ATC controlled).

Permanently closed runways and taxiways have their lighting circuits disconnected, and the runway threshold, runway designation, and touchdown markings are obliterated. Yellow crosses are painted on each end of the runway and at 1,000-foot intervals.

Temporarily closed runways and taxiways can be identified by yellow crosses. A cross may be placed on each runway end instead of permanent markings.

Control of Airport Lighting

ATC controls airport lighting at towered airports. A pilot may request various light systems be turned on or off and also request a specified intensity, if available.

At nontowered airports, the lights may be on a day/night timer, or the pilot may control the lighting by radio. The lighting intensity can be changed by selecting a specified frequency and clicking the radio microphone. Lights typically remain on the selected intensity for 15 minutes.

Airport Beacons

Airport and heliport beacons have a vertical light distribution, making them most effective from 1° to 10° above the horizon. The beacon may be an omni-directional capacitor-discharge device, or it may rotate at a constant speed, producing the visual effect of flashes at regular intervals.

Airport Beacon Operation During Daylight Hours

In Class B, Class C, Class D, and Class E surface areas, the operation of the airport beacon during daylight hours indicates that the ground visibility is less than 3 SM or the ceiling is less than 1,000' (unless it was mistakenly left on). An ATC clearance is required for landing, takeoff, and flight in the traffic pattern.

There is no regulatory requirement for daylight beacon operation. Pilots should not rely solely on the airport beacon's operation to indicate if weather conditions are IFR or VFR.