13-1

Introduction

Each time a pilot operates an aircraft, the flight normally 

begins and ends at an airport. An airport may be a small sod 

field or a large complex utilized by air carriers. This chapter 

examines airport operations, identifies features of an airport 

complex, and provides information on operating on or in the 

vicinity of an airport.

Types of Airports

There are two types of airports—towered and nontowered. 

These types can be further subdivided to:

• Civil Airports—airports that are open to the general 

public.

• Military/Federal Government airports—airports 

operated by the military, National Aeronautics and 

Space Administration (NASA), or other agencies of 

the Federal Government.

• Private airports—airports designated for private or 

restricted use only, not open to the general public. 

Airport 

Operations

Chapter 13
13-2

Outbound Inbound Practice Instrument

Approach

UNICOM

(no tower or FSS)

No tower, FSS,

or UNICOM

No tower in 

operation, FSS open

FSS closed

(no tower)

Tower or FSS

not in operation

Communicate with UNICOM 

station on published CTAF 

frequency (122.7, 122.8, 122.725, 

122.975, or 123.0). If unable to 

contact UNICOM station, use selfannounce procedures on CTAF.

Self-announce on MULTICOM 

frequency 122.9.

Communicate with FSS on CTAF 

frequency.

Self-announce on CTAF.

Self-announce on CTAF.

Before taxiing and

before taxiing on the

runway for departure.

Before taxiing and

before taxiing on the

runway for departure.

Before taxiing and

before taxiing on the

runway for departure.

Before taxiing and

before taxiing on the

runway for departure.

Before taxiing and

before taxiing on the

runway for departure.

10 miles out.

Entering downwind,

base, and final.

Leaving the runway.

10 miles out.

Entering downwind,

base, and final.

Leaving the runway.

10 miles out.

Entering downwind,

base, and final.

Leaving the runway.

10 miles out.

Entering downwind,

base, and final.

Leaving the runway.

10 miles out.

Entering downwind,

base, and final.

Leaving the runway.

Facility at Airport Frequency Use

Cummunication/Broadcast Procedures

Departing final

approach fix (name) 

or on final approach

segment inbound.

Approach

completed/terminated.

Figure 13-1. Recommended communication procedures.

Towered Airport

A towered airport has an operating control tower. Air traffic 

control (ATC) is responsible for providing the safe, orderly, 

and expeditious flow of air traffic at airports where the 

type of operations and/or volume of traffic requires such a 

service. Pilots operating from a towered airport are required 

to maintain two-way radio communication with air traffic 

controllers, and to acknowledge and comply with their 

instructions. Pilots must advise ATC if they cannot comply 

with the instructions issued and request amended instructions. 

A pilot may deviate from an air traffic instruction in an 

emergency, but must advise ATC of the deviation as soon 

as possible.

Nontowered Airport

An nontowered airport does not have an operating control 

tower. Two-way radio communications are not required, 

although it is a good operating practice for pilots to transmit 

their intentions on the specified frequency for the benefit 

of other traffic in the area. The key to communicating at 

an airport without an operating control tower is selection 

of the correct common frequency. The acronym CTAF, 

which stands for Common Traffic Advisory Frequency, 

is synonymous with this program. A CTAF is a frequency 

designated for the purpose of carrying out airport advisory 

practices while operating to or from an airport without an 

operating control tower. The CTAF may be a Universal 

Integrated Community (UNICOM), MULTICOM, Flight 

Service Station (FSS), or tower frequency and is identified 

in appropriate aeronautical publications. UNICOM is a 

nongovernment air/ground radio communication station 

which may provide airport information at public use airports 

where there is no tower or FSS. On pilot request, UNICOM 

stations may provide pilots with weather information, wind 

direction, the recommended runway, or other necessary 

information. If the UNICOM frequency is designated as 

the CTAF, it will be identified in appropriate aeronautical 

publications. Figure 13-1 lists recommended communication 

procedures. More information on radio communications is 

discussed later in this chapter.

Sources for Airport Data

When a pilot flies into a different airport, it is important to 

review the current data for that airport. This data provides the 

pilot with information, such as communication frequencies, 

services available, closed runways, or airport construction. 

Three common sources of information are:

• Aeronautical Charts

• Airport/Facility Directory (A/FD)

• Notices to Airmen (NOTAMs)
13-3

Figure 13-2. Airport/Facility Directory excerpt.

Aeronautical Charts

Aeronautical charts provide specific information on airports. 

Chapter 15, Navigation, contains an excerpt from an 

aeronautical chart and an aeronautical chart legend, which 

provides guidance on interpreting the information on the 

chart.

Airport/Facility Directory (A/FD)

The A/FD provides the most comprehensive information on 

a given airport. It contains information on airports, heliports, 

and seaplane bases that are open to the public. The A/FD is 

published in seven books, which are organized by regions and 

are revised every 56 days. The A/FD is also available digitally 

at www.naco.faa.gov. Figure 13-2 contains an excerpt from 

a directory. For a complete listing of information provided 

in an A/FD and how the information may be decoded, refer 

to the “Directory Legend Sample” located in the front of 

each A/FD.

In addition to airport information, each A/FD contains 

information such as special notices, Federal Aviation 

Administration (FAA) and National Weather Service (NWS) 

telephone numbers, preferred instrument flight rules (IFR) 

routing, visual flight rules (VFR) waypoints, a listing of very 

high frequency (VHF) omnidirectional range (VOR) receiver 

checkpoints, aeronautical chart bulletins, land and hold short 

operations (LAHSO) for selected airports, airport diagrams 

for selected towered airports, en route flight advisory 

service (EFAS) outlets, parachute jumping areas, and facility 

telephone numbers. It would be helpful to review an A/FD to 

become familiar with the information it contains.

Notices to Airmen (NOTAMs)

NOTAMs provide the most current information available. 

They provide time-critical information on airports and 

changes that affect the national airspace system (NAS) and 

are of concern to IFR operations. NOTAM information is 

classified into three categories. These are NOTAM-D or 

distant, NOTAM-L or local, and flight data center (FDC) 

NOTAMs. NOTAM-Ds are attached to hourly weather 

reports and are available at automated flight service stations 

(AFSS) or FSS. 

FDC NOTAMs are issued by the National Flight Data Center 

and contain regulatory information, such as temporary 

flight restrictions or an amendment to instrument approach 
13-4

19

A

4

A

Terminal

LEGEND

4

In-Pavement Runway Guard Lights

Elevated Runway Guard Lights

Stop Bar

Centerline/Lead-On Lights

Clearance Bar Lights

Position Marking

Taxiway Edge Marking (Do Not Cross)

Surface Painted

Runway Marking

Stop Bar/ILS Hold

Non-Movement Area

Vehicle Lanes

(Zipper Style)

Taxiway/Taxiway Hold Marking

Hold Marking for

Land and Hold 

Short Operations

Figure 13-3. Selected airport markings and surface lighting.

procedures. The NOTAM-Ds and FDC NOTAMs are 

contained in the NOTAM publication, which is issued every 

28 days. Prior to any flight, pilots should check for any 

NOTAMs that could affect their intended flight.

NOTAM-D information includes such data as taxiway 

closures, personnel and equipment near or crossing runways, 

and airport lighting aids that do not affect instrument 

approach criteria, such as visual approach slope indicator 

(VASI). NOTAM-D information is distributed locally only 

and is not attached to the hourly weather reports. A separate 

file of local NOTAMs is maintained at each FSS for facilities 

in their area only. NOTAM-D information for other FSS areas 

must be specifically requested directly from the FSS that has 

responsibility for the airport concerned. 

Airport Markings and Signs

There are markings and signs used at airports, which provide 

directions and assist pilots in airport operations. Some of the 

most common markings and signs are discussed. Additional 

information may be found in Chapter 2, Aeronautical 

Lighting and Other Airport Visual Aids, in the Aeronautical 

Information Manual (AIM).

Runway Markings

Runway markings vary depending on the type of operations 

conducted at the airport. Figure 13-3 shows a runway that 

is approved as a precision instrument approach runway and 

some other common runway markings. A basic VFR runway 

may only have centerline markings and runway numbers.
13-5

Roadway edge stripes,

white, continuous 6"

(15 cm) wide

Roadway stop line,

white, 2' (0.67 m) wide,

across the approach

lane (see text for 

additional requirements)

Roadway edge 

stripes (see text) 

white, zipper style

Roadway lane line 

white 6" (15 cm) 

wide dashes 15' 

(4.5 m) long with 

spaces between 

dashes 25' (7.5 m) 

long

Taxiway centerline marking

Taxiway edge marking (dashed) Not to scale

Figure 13-4. Vehicle roadway markings.

Since aircraft are affected by the wind during takeoffs 

and landings, runways are laid out according to the local 

prevailing winds. Runway numbers are in reference to 

magnetic north. Certain airports have two or even three 

runways laid out in the same direction. These are referred to 

as parallel runways and are distinguished by a letter added 

to the runway number (e.g., runway 36L (left), 36C (center), 

and 36R (right)).

Another feature of some runways is a displaced threshold. A 

threshold may be displaced because of an obstruction near 

the end of the runway. Although this portion of the runway 

is not to be used for landing, it may be available for taxiing, 

takeoff, or landing rollout. Some airports may have a blast 

pad/stopway area. The blast pad is an area where a propeller 

or jet blast can dissipate without creating a hazard. The 

stopway area is paved in order to provide space for an aircraft 

to decelerate and stop in the event of an aborted takeoff. These 

areas cannot be used for takeoff or landing.

Taxiway Markings

Aircraft use taxiways to transition from parking areas to the 

runway. Taxiways are identified by a continuous yellow 

centerline stripe and may include edge markings to define the 

edge of the taxiway. This is usually done when the taxiway 

edge does not correspond with the edge of the pavement. If an 

edge marking is a continuous line, the paved shoulder is not 

intended to be used by an aircraft. If it is a dashed marking, 

an aircraft may use that portion of the pavement. Where a 

taxiway approaches a runway, there may be a holding position 

marker. These consist of four yellow lines (two solid and two 

dashed). The solid lines are where the aircraft is to hold. At 

some towered airports, holding position markings may be 

found on a runway. They are used when there are intersecting 

runways, and ATC issues instructions such as “cleared to 

land—hold short of runway 30.”

Other Markings

Some other markings found on the airport include vehicle 

roadway markings, VOR receiver checkpoint markings, and 

non-movement area boundary markings.

Vehicle roadway markings are used when necessary to define 

a pathway for vehicle crossing areas that are also intended 

for aircraft. These markings usually consist of a solid white 

line to delineate each edge of the roadway and a dashed line 

to separate lanes within the edges of the roadway. In lieu of 

the solid lines, zipper markings may be used to delineate the 

edges of the vehicle roadway. [Figure 13-4]

A VOR receiver checkpoint marking consists of a painted 

circle with an arrow in the middle. The arrow is aligned in 

the direction of the checkpoint azimuth. This allows pilots to 

check aircraft instruments with navigational aid signals.
13-6

Airport Sign Systems

Type of Sign Action or Purpose Type of Sign Action or Purpose

4-22

8-APCH

ILS

4

B

22

26-8

J

L

22

MIL

A G L

Taxiway/Runway Hold Position:

Hold short of runway on taxiway

Runway Approach Hold Position:

Hold short of aircraft on approach

ILS Critical Area Hold Position:

Hold short of ILS approach critical area

No Entry:

Identifies paved areas where aircraft entry is

prohibited

Taxiway Location:

Identifies taxiway on which aircraft is located

Runway Location:

Identifies runway on which aircraft is located

Runway Distance Remaining:

Provides remaining runway length in 1,000

feet increments

Runway/Runway Hold Position:

Hold short of intersecting runway

Runway Exit:

Defines direction & designation of exit 

taxiway from runway

Taxiway Direction:

Defines direction & designation of 

intersecting taxiway(s)

Runway Safety Area/Obstacle Free

Zone Boundary:

Exit boundary of runway protected areas

ILS Critical Area Boundary:

Exit boundary of ILS critical area

Outbound Destination:

Defines directions to takeoff runways

Inbound Destination:

Defines directions for arriving aircraft

Taxiway Ending Marker:

Indicates taxiway does not continue

Direction Sign Array:

Identifies location in conjunction with

multiple intersecting taxiways

Figure 13-5. Airport signs. 

A non-movement area boundary marking delineates a 

movement area under ATC. These markings are yellow and 

located on the boundary between the movement and nonmovement area. They normally consist of two yellow lines 

(one solid and one dashed).

Airport Signs

There are six types of signs that may be found at airports. The 

more complex the layout of an airport, the more important 

the signs become to pilots. Figure 13-5 shows examples of 

signs, their purpose, and appropriate pilot action. The six 

types of signs are:

• Mandatory instruction signs—red background with 

white inscription. These signs denote an entrance to a 

runway, critical area, or prohibited area.

• Location signs—black with yellow inscription and a 

yellow border, no arrows. They are used to identify a 

taxiway or runway location, to identify the boundary 

of the runway, or identify an instrument landing 

system (ILS) critical area.

• Direction signs—yellow background with black 

inscription. The inscription identifies the designation 

of the intersecting taxiway(s) leading out of an 

intersection.

• Destination signs—yellow background with black 

inscription and also contain arrows. These signs 

provide information on locating things, such as 

runways, terminals, cargo areas, and civil aviation 

areas. 

• Information signs—yellow background with black 

inscription. These signs are used to provide the pilot 

with information on such things as areas that cannot 

be seen from the control tower, applicable radio 

frequencies, and noise abatement procedures. The 

airport operator determines the need, size, and location 

of these signs.

• Runway distance remaining signs—black background 

with white numbers. The numbers indicate the distance 

of the remaining runway in thousands of feet.

Airport Lighting

The majority of airports have some type of lighting for night 

operations. The variety and type of lighting systems depends 

on the volume and complexity of operations at a given airport. 

Airport lighting is standardized so that airports use the same 

light colors for runways and taxiways.

Airport Beacon

Airport beacons help a pilot identify an airport at night. 

The beacons are operated from dusk till dawn. Sometimes 

they are turned on if the ceiling is less than 1,000 feet and/

or the ground visibility is less than 3 statute miles (VFR 

minimums). However, there is no requirement for this, so 

a pilot has the responsibility of determining if the weather 

meets VFR requirements. The beacon has a vertical light 
13-7

White Green White Yellow

Figure 13-6. Airport rotating beacons.

Below Glidepath On Glidepath Above Glidepath

Far Bar

Near Bar

Far Bar

Near Bar

Far Bar

Near Bar

Figure 13-7. Two-bar VASI system.

distribution to make it most effective from 1–10° above the 

horizon, although it can be seen well above or below this 

spread. The beacon may be an omnidirectional capacitordischarge device, or it may rotate at a constant speed, which 

produces the visual effect of flashes at regular intervals. The 

combination of light colors from an airport beacon indicates 

the type of airport. [Figure 13-6] Some of the most common 

beacons are:

• Flashing white and green for civilian land airports;

• Flashing white and yellow for a water airport;

• Flashing white, yellow, and green for a heliport; and

• Two quick white flashes alternating with a green flash 

identifying a military airport.

Approach Light Systems

Approach light systems are primarily intended to provide a 

means to transition from instrument flight to visual flight for 

landing. The system configuration depends on whether the 

runway is a precision or nonprecision instrument runway. 

Some systems include sequenced flashing lights, which 

appear to the pilot as a ball of light traveling toward the 

runway at high speed. Approach lights can also aid pilots 

operating under VFR at night.

Visual Glideslope Indicators

Visual glideslope indicators provide the pilot with glidepath 

information that can be used for day or night approaches. By 

maintaining the proper glidepath as provided by the system, 

a pilot should have adequate obstacle clearance and should 

touch down within a specified portion of the runway.

Visual Approach Slope Indicator (VASI)

VASI installations are the most common visual glidepath 

systems in use. The VASI provides obstruction clearance 

within 10° of the runway extended runway centerline, and to 

four nautical miles (NM) from the runway threshold.

The VASI consists of light units arranged in bars. There are 

2-bar and 3-bar VASIs. The 2-bar VASI has near and far 

light bars and the 3-bar VASI has near, middle, and far light 

bars. Two-bar VASI installations provide one visual glidepath 

which is normally set at 3°. The 3-bar system provides two 

glidepaths, the lower glidepath normally set at 3° and the 

upper glidepath 1⁄4 degree above the lower glidepath. 

The basic principle of the VASI is that of color differentiation 

between red and white. Each light unit projects a beam of 

light, a white segment in the upper part of the beam and a 

red segment in the lower part of the beam. The lights are 

arranged so the pilot sees the combination of lights shown in 

Figure 13-7 to indicate below, on, or above the glidepath.

Other Glidepath Systems

A precision approach path indicator (PAPI) uses lights similar 

to the VASI system except they are installed in a single row, 

normally on the left side of the runway. [Figure 13-8]

A tri-color system consists of a single light unit projecting 

a three-color visual approach path. Below the glidepath is 

indicated by red, on the glidepath is indicated by green, and 

above the glidepath is indicated by amber. When descending 

below the glidepath, there is a small area of dark amber. Pilots 

should not mistake this area for an “above the glidepath” 

indication. [Figure 13-9] 

Pulsating visual approach slope indicators normally consist of 

a single light unit projecting a two-color visual approach path 

into the final approach area of the runway upon which the 

indicator is installed. The on glidepath indication is a steady 

white light. The slightly below glidepath indication is a steady 

red light. If the aircraft descends further below the glidepath, 

the red light starts to pulsate. The above glidepath indication 

is a pulsating white light. The pulsating rate increases as the 

aircraft gets further above or below the desired glideslope. 
13-8

Below glidepath

Above glidepath

On glidepath

Pulsating

white

Steady red

Steady

white

Threshold

Slightly below glidepath Pulsating red

Figure 13-10. Pulsating visual approach slope indicator.

Below glidepath

Above glidepath

On glidepath

Amber

Red

Green

Amber

Figure 13-9. Tri-color visual approach slope indicator.

High

more than 3.5°

Slightly High

 3.2°

On Glidepath

 3°

Slightly Low

 2.8°

Low

less than 2.5°

Figure 13-8. Precision approach path indicator.

The useful range of the system is about four miles during the 

day and up to ten miles at night. [Figure 13-10]

Runway Lighting

There are various lights that identify parts of the runway 

complex. These assist a pilot in safely making a takeoff or 

landing during night operations.

Runway End Identifier Lights (REIL)

Runway end identifier lights (REIL) are installed at many 

airfields to provide rapid and positive identification of the 

approach end of a particular runway. The system consists 

of a pair of synchronized flashing lights located laterally 

on each side of the runway threshold. REILs may be either 

omnidirectional or unidirectional facing the approach area.

Runway Edge Lights

Runway edge lights are used to outline the edges of runways 

at night or during low visibility conditions. These lights 

are classified according to the intensity 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 have variable intensity 

settings. These lights are white, except on instrument runways 
13-9

Key Mike Function

Highest intensity available

Medium or lower intensity

(Lower REIL or REIL off)

Lowest intensity available

(Lower REIL or REIL off)

7 times within 5 seconds

5 times within 5 seconds

3 times within 5 seconds

Figure 13-11. Radio controlled runway lighting.

Control of Airport Lighting

Airport lighting is controlled by air traffic controllers at 

towered airports. At nontowered airports, the lights may 

be on a timer, or where an FSS is located at an airport, the 

FSS personnel may control the lighting. A pilot may request 

various light systems be turned on or off and also request a 

specified intensity, if available, from ATC or FSS personnel. 

At selected nontowered airports, the pilot may control the 

lighting by using the radio. This is done by selecting a 

specified frequency and clicking the radio microphone. For 

information on pilot controlled lighting at various airports, 

refer to the A/FD. [Figure 13-11]

Taxiway Lights

Omnidirectional taxiway lights outline the edges of the 

taxiway and are blue in color. At many airports, these edge 

lights may have variable intensity settings that may be 

adjusted by an air traffic controller when deemed necessary 

or when requested by the pilot. Some airports also have 

taxiway centerline lights that are green in color.

Obstruction Lights

Obstructions are marked or lighted to warn pilots of 

their presence during daytime and nighttime conditions. 

Obstruction lighting can be found both on and off an airport 

to identify obstructions. They may be marked or lighted in 

any of the following conditions.

• Red obstruction lights—flash or emit a steady red color 

during nighttime operations, and the obstructions are 

painted orange and white for daytime operations.

• High intensity white obstruction lights—flash high 

intensity white lights during the daytime with the 

intensity reduced for nighttime.

• Dual lighting—a combination of flashing red beacons 

and steady red lights for nighttime operation, and high 

intensity white lights for daytime operations.

where amber lights are used on the last 2,000 feet or half the 

length of the runway, whichever is less. The lights marking 

the end of the runway are red.

In-Runway Lighting

Runway centerline lighting system (RCLS)—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 feet of the runway. The 

white lights begin to alternate with red for the next 2,000 feet. 

For the remaining 1,000 feet of the runway, all centerline 

lights are red. 

Touchdown zone lights (TDZL)—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 steadyburning white lights which start 100 feet beyond the landing 

threshold and extend to 3,000 feet beyond the landing 

threshold or to the midpoint of the runway, whichever is 

less. 

Taxiway centerline lead-off lights—provide visual guidance 

to persons exiting the runway. They are color-coded to warn 

pilots and vehicle drivers that they are within the runway 

environment or ILS/MLS critical area, whichever is more 

restrictive. Alternate green and yellow lights are installed, 

beginning with green, from the runway centerline to one 

centerline light position beyond the runway holding position 

or ILS/MLS critical area holding position. 

Taxiway centerline lead-on lights—provide visual guidance 

to persons entering the runway. These “lead-on” lights 

are also color-coded with the same color pattern as leadoff lights to warn pilots and vehicle drivers that they are 

within the runway environment or instrument landing 

system/microwave landing system (ILS/MLS) critical area, 

whichever is more conservative. The fixtures used for lead-on 

lights are bidirectional (i.e., one side emits light for the leadon function while the other side emits light for the lead-off 

function). Any fixture that emits yellow light for the lead-off 

function also emits yellow light for the lead-on function. 

Land and hold short lights—used to indicate the hold short 

point on certain runways which are approved for LAHSO. 

Land and hold short lights consist of a row of pulsing white 

lights installed across the runway at the hold short point. 

Where installed, the lights are on anytime LAHSO is in effect. 

These lights are off when LAHSO is not in effect. 
13-10

Tetrahedron

Wind Sock or Cone

Wind Tee

WIND

Figure 13-12. Wind direction indicators.

Wind Direction Indicators

It is important for a pilot to know the direction of the wind. 

At facilities with an operating control tower, this information 

is provided by ATC. Information may also be provided by 

FSS personnel located at a particular airport or by requesting 

information on a CTAF at airports that have the capacity to 

receive and broadcast on this frequency.

When none of these services is available, it is possible to 

determine wind direction and runway in use by visual wind 

indicators. A pilot should check these wind indicators even 

when information is provided on the CTAF at a given airport 

because there is no assurance that the information provided 

is accurate. 

The wind direction indicator can be a wind cone, wind sock, 

tetrahedron, or wind tee. These are usually located in a central 

location near the runway and may be placed in the center 

of a segmented circle, which identifies the traffic pattern 

direction, if it is other than the standard left-hand pattern. 

[Figures 13-12 and 13-13] 

The wind sock is a good source of information since it not 

only indicates wind direction, but allows the pilot to estimate 

the wind velocity and gusts or factor. The wind sock extends 

out straighter in strong winds and tends to move back and 

forth when the wind is gusty. Wind tees and tetrahedrons can 

swing freely, and align themselves with the wind direction. 

The wind tee and tetrahedron can also be manually set to 

align with the runway in use; therefore, a pilot should also 

look at the wind sock, if available.

Traffic Patterns 

At those airports without an operating control tower, a 

segmented circle visual indicator system [Figure 13-13], if 

installed, is designed to provide traffic pattern information. 

Usually located in a position affording maximum visibility 

to pilots in the air and on the ground and providing a 

centralized location for other elements of the system, the 

segmented circle consists of the following components: wind 

direction indicators, landing direction indicators, landing strip 

indicators, and traffic pattern indicators.

A tetrahedron is installed to indicate the direction of landings 

and takeoffs when conditions at the airport warrant its use. 

It may be located at the center of a segmented circle and 

may be lighted for night operations. The small end of the 

tetrahedron points in the direction of landing. Pilots are 

cautioned against using a tetrahedron for any purpose other 

than as an indicator of landing direction. At airports with 

control towers, the tetrahedron should only be referenced 

when the control tower is not in operation. Tower instructions 

supersede tetrahedron indications.

Landing strip indicators are installed in pairs as shown in 

Figure 13-13 and are used to show the alignment of landing 

strips. Traffic pattern indicators are arranged in pairs in 

conjunction with landing strip indicators and used to indicate 

the direction of turns when there is a variation from the 

normal left traffic pattern. (If there is no segmented circle 

installed at the airport, traffic pattern indicators may be 

installed on or near the end of the runway.) 
13-11

Landing Runway Wind Cone

or Landing Strip 

Indicators

Landing Direction

Indicator

Traffic Pattern

Indicators

Figure 13-13. Segmented circle.

At most airports and military air bases, traffic pattern altitudes 

for propeller-driven aircraft generally extend from 600 feet 

to as high as 1,500 feet above ground level (AGL). Pilots can 

obtain the traffic pattern altitude for an airport from the A/FD. 

Also, traffic pattern altitudes for military turbojet aircraft 

sometimes extend up to 2,500 feet AGL. Therefore, pilots 

of en route aircraft should be constantly on the alert for other 

aircraft in traffic patterns and avoid these areas whenever 

possible. When operating at an airport, traffic pattern 

altitudes should be maintained unless otherwise required 

by the applicable distance from cloud criteria in Title 14 of 

the Code of Federal Regulations (14 CFR) section 91.155. 

Additional information on airport traffic pattern operations 

can be found in Chapter 4, Air Traffic Control, of the AIM. 

Pilots can find traffic pattern information and restrictions 

such as noise abatement in the A/FD.

Example: Key to Traffic Pattern Operations—

Single Runway

1. Enter pattern in level flight, abeam the midpoint 

of the runway, at pattern altitude. (1,000' AGL) is 

recommended pattern altitude unless established 

otherwise.) 

2. Maintain pattern altitude until abeam approach end of 

the landing runway on downwind leg.

3. Complete turn to final at least 1⁄4 mile from the 

runway.

4. Continue straight ahead until beyond departure end 

of runway.

5. If remaining in the traffic pattern, commence turn to 

crosswind leg beyond the departure end of the runway 

within 300 feet of pattern altitude.

6. If departing the traffic pattern, continue straight out, 

or exit with a 45° turn (to the left when in a left-hand 

traffic pattern; to the right when in a right-hand traffic 

pattern) beyond the departure end of the runway, after 

reaching pattern altitude. [Figure 13-14]

Example: Key to Traffic Pattern Operations—

Parallel Runways

1. Enter pattern in level flight, abeam the midpoint 

of the runway, at pattern altitude. (1,000' AGL is 

recommended pattern altitude unless established 

otherwise.) 

2. Maintain pattern altitude until abeam approach end of 

the landing runway on downwind leg.

3. Complete turn to final at least 1⁄4 mile from the 

runway.

4. Continue straight ahead until beyond departure end 

of runway.

5. If remaining in the traffic pattern, commence turn to 

crosswind leg beyond the departure end of the runway 

within 300 feet of pattern altitude.

6. If departing the traffic pattern, continue straight out, 

or exit with a 45° turn (to the left when in a left-hand 

traffic pattern; to the right when in a right-hand traffic 

pattern) beyond the departure end of the runway, after 

reaching pattern altitude.

7. Do not overshoot final or continue on a track which 

penetrates the final approach of the parallel runway.

8. Do not continue on a track which penetrates the departure 

path of the parallel runway. [Figure 13-15]

Radio Communications

Operating in and out of a towered airport, as well as in a 

good portion of the airspace system, requires that an aircraft 

have two-way radio communication capability. For this 

reason, a pilot should be knowledgeable of radio station 

license requirements and radio communications equipment 

and procedures.

Radio License

There is no license requirement for a pilot operating in the 

United States; however, a pilot who operates internationally 

is required to hold a restricted radiotelephone permit issued 

by the Federal Communications Commission (FCC). There 
13-12

LEGEND

Recommended Standard Left-Hand Traffic 

pattern (depicted)

(Standard right-hand traffic pattern would be mirror image)

RUNWAY

Final Departure

Downwind

Base

Crosswind

Departure

Departure

Entry

Traffic Pattern Indicators

Application of Traffic

Pattern Indicators

Segmented Circle

Wind Cone

Landing Runway

(or Landing Strip Indicators)

Landing Direction Indicator

Hazard or Populated Area

Figure 13-14. Traffic pattern operations—single runway.

is also no station license requirement for most general 

aviation aircraft operating in the United States. A station 

license is required however for an aircraft which is operating 

internationally, which uses other than a VHF radio, and which 

meets other criteria.

Radio Equipment

In general aviation, the most common types of radios are 

VHF. A VHF radio operates on frequencies between 118.0 

and 136.975 and is classified as 720 or 760 depending 

on the number of channels it can accommodate. The 720 

and 760 use .025 spacing (118.025, 118.050) with the 720 

having a frequency range up to 135.975 and the 760 going 

up to 136.975. VHF radios are limited to line of sight 

transmissions; therefore, aircraft at higher altitudes are able 

to transmit and receive at greater distances.

In March of 1997, the International Civil Aviation 

Organization (ICAO) amended its International Standards 

and Recommended Practices to incorporate a channel plan 

specifying 8.33 kHz channel spacings in the Aeronautical 

Mobile Service. The 8.33 kHz channel plan was adopted to 

alleviate the shortage of VHF ATC channels experienced in 

western Europe and in the United Kingdom. Seven western 

European countries and the United Kingdom implemented 

the 8.33 kHz channel plan on January 1, 1999. Accordingly, 

aircraft operating in the airspace of these countries must have 

the capability of transmitting and receiving on the 8.33 kHz 

spaced channels.

Using proper radio phraseology and procedures contribute to 

a pilot’s ability to operate safely and efficiently in the airspace 

system. A review of the Pilot/Controller Glossary contained 

in the AIM assists a pilot in the use and understanding of 

standard terminology. The AIM also contains many examples 

of radio communications.

ICAO has adopted a phonetic alphabet, which should be 

used in radio communications. When communicating with 

ATC, pilots should use this alphabet to identify their aircraft. 

[Figure 13-16]

Lost Communication Procedures

It is possible that a pilot might experience a malfunction of 

the radio. This might cause the transmitter, receiver, or both 

to become inoperative. If a receiver becomes inoperative and 

a pilot needs to land at a towered airport, it is advisable to 

remain outside or above Class D airspace until the direction 

and flow of traffic is determined. A pilot should then advise 

the tower of the aircraft type, position, altitude, and intention 

to land. The pilot should continue, enter the pattern, report a 

position as appropriate, and watch for light signals from the 

tower. Light signal colors and their meanings are contained 

in Figure 13-17.
13-13

LEGEND

Standard Left-Hand 

Traffic Pattern (depicted)

Right-HandTraffic

Pattern (depicted)

Final Departure

Base

Crosswind

Final Departure

Base

Crosswind

Downwind

Entry

Traffic Pattern

Indicators

Segmented Circle

Wind Cone

Landing Runway

(or Landing Strip Indicators)

Landing Direction

Indicator

No Transgression Zone No Transgression Zone

Figure 13-15. Traffic pattern operation—parallel runways.

If the transmitter becomes inoperative, a pilot should 

follow the previously stated procedures and also monitor 

the appropriate ATC frequency. During daylight hours ATC 

transmissions may be acknowledged by rocking the wings, 

and at night by blinking the landing light.

When both receiver and transmitter are inoperative, the pilot 

should remain outside of Class D airspace until the flow of 

traffic has been determined and then enter the pattern and 

watch for light signals.

If a radio malfunctions prior to departure, it is advisable to 

have it repaired, if possible. If this is not possible, a call should 

be made to ATC and the pilot should request authorization 

to depart without two-way radio communications. If 

authorization is given to depart, the pilot is advised to monitor 

the appropriate frequency and/or watch for light signals as 

appropriate.

Air Traffic Control (ATC) Services

Besides the services provided by an FSS as discussed in 

Chapter 12, Aviation Weather Services, numerous other 

services are provided by ATC. In many instances a pilot 

is required to have contact with ATC, but even when not 

required, a pilot finds it helpful to request their services.

Primary Radar

Radar is a device which provides information on range, 

azimuth, and/or elevation of objects in the path of the 

transmitted pulses. It measures the time interval between 

transmission and reception of radio pulses and correlates the 

angular orientation of the radiated antenna beam or beams in 

azimuth and/or elevation. Range is determined by measuring 

the time it takes for the radio wave to go out to the object 

and then return to the receiving antenna. The direction of a 

detected object from a radar site is determined by the position 
13-14

Character Morse Code Telephony Phonic Pronunciation

0

9

8

7

6

5

4

3

2

1

Z

Y

X

W

V

U

T

S

R

Q

P

O

N

M

L

K

J

I

H

G

F

E

D

C

B

A

Figure 13-16. Phonetic alphabet.

of the rotating antenna when the reflected portion of the radio 

wave is received.

Modern radar is very reliable and there are seldom outages. 

This is due to reliable maintenance and improved equipment. 

There are, however, some limitations which may affect ATC 

services and prevent a controller from issuing advisories 

concerning aircraft which are not under his or her control 

and cannot be seen on radar.

The characteristics of radio waves are such that they normally 

travel in a continuous straight line unless they are “bent” by 

atmospheric phenomena such as temperature inversions, 

reflected or attenuated by dense objects such as heavy clouds 

and precipitation, or screened by high terrain features.

ATC Radar Beacon System (ATCRBS)

The ATC radar beacon system (ATCRBS) is often referred 

to as “secondary surveillance radar.” This system consists 

of three components and helps in alleviating some of 

the limitations associated with primary radar. The three 

components are an interrogator, transponder, and radarscope. 

The advantages of ATCRBS are the reinforcement of radar 

targets, rapid target identification, and a unique display of 

selected codes.

Transponder

The transponder is the airborne portion of the secondary 

surveillance radar system and a system with which a 

pilot should be familiar. The ATCRBS cannot display the 

secondary information unless an aircraft is equipped with 

a transponder. A transponder is also required to operate 

in certain controlled airspace as discussed in Chapter 14, 

Airspace.

A transponder code consists of four numbers from 0 to 7 

(4,096 possible codes). There are some standard codes, or 

ATC may issue a four-digit code to an aircraft. When a 

controller requests a code or function on the transponder, the 

word “squawk” may be used. Figure 13-18 lists some standard 

transponder phraseology. Additional information concerning 

transponder operation can be found in the AIM, chapter 4.

Radar Traffic Advisories

Radar equipped ATC facilities provide radar assistance to 

aircraft on instrument flight plans and VFR aircraft provided 

the aircraft can communicate with the facility and are within 

radar coverage. This basic service includes safety alerts, traffic 

advisories, limited vectoring when requested, and sequencing 

at locations where this procedure has been established. ATC 

issues traffic advisories based on observed radar targets. The 

traffic is referenced by azimuth from the aircraft in terms of 

the 12-hour clock. Also, distance in nautical miles, direction 

in which the target is moving, and type and altitude of the 

aircraft, if known, are given. An example would be: “Traffic 

10 o’clock 5 miles east bound, Cessna 152, 3,000 feet.” The 

pilot should note that traffic position is based on the aircraft 

track, and that wind correction can affect the clock position 
13-15

Radar Beacon Phraseology

SQUAWK (number)

IDENT

SQUAWK (number) and IDENT

SQUAWK Standby

SQUAWK Low/Normal

SQUAWK Altitude

STOP Altitude SQUAWK

STOP SQUAWK (mode in use)

STOP SQUAWK

SQUAWK Mayday

SQUAWK VFR

Operate radar beacon transponder on designated code in MODE A/3.

Engage the “IDENT” feature (military I/P) of the transponder.

Operate transponder on specified code in MODE A/3 and engage the “IDENT”

(military I/P) feature.

Switch transponder to standby position.

Operate transponder on low or normal sensitivity as specified. Transponder is 

operated in “NORMAL” position unless ATC specifies “LOW” (“ON” is used instead of 

“NORMAL” as a master control label on some types of transponders).

Activate MODE C with automatic altitude reporting.

Turn off altitude reporting switch and continue transmitting MODE C framing pulses. 

If your equipment does not have this capability, turn off MODE C.

Switch off specified mode. (Used for military aircraft when the controller is unaware of

military service requirements for the aircraft to continue operation on another MODE.)

Switch off transponder.

Operate transponder in the emergency position (MODE A Code 7700 for civil 

transponder, MODE 3 Code 7700 and emergency feature for military transponder).

Operate radar beacon transponder on Code 1200 in MODE A/3, or other 

appropriate VFR code.

Figure 13-18. Transponder phraseology.

Color and Type of Signal Aircraft on the Ground Movement of Vehicles,

Equipment and Personnel Aircraft in Flight

Steady green

Flashing green

Steady red

Flashing red

Flashing white

Alternating red and green

Cleared to cross, proceed or go

Not applicable

Stop

Clear the taxiway/runway

Return to starting point

on airport

Exercise extreme caution!!!!

Cleared for takeoff

Cleared for taxi

Stop

Taxi clear of the runway

in use

Return to starting point

on airport

Exercise extreme caution!!!!

Cleared to land

Return for landing (to be followed 

by steady green at the proper time)

Give way to other aircraft and

continue circling

Airport unsafe, do not land

Not applicable

Exercise extreme caution!!!!

Figure 13-17. Light gun signals.

sequencing of VFR aircraft to the primary airport. Class B 

service provides approved separation of aircraft based on 

IFR, VFR, and/or weight, and sequencing of VFR arrivals 

to the primary airport(s).

Wake Turbulence

All aircraft generate wake turbulence while in flight. This 

disturbance is caused by a pair of counter-rotating vortices 

trailing from the wingtips. The vortices from larger aircraft 

pose problems to encountering aircraft. The wake of these 

aircraft can impose rolling moments exceeding the rollat which a pilot locates traffic. This service is not intended to 

relieve the pilot of the responsibility to see and avoid other 

aircraft. [Figure 13-19]

In addition to basic radar service, terminal radar service area 

(TRSA) has been implemented at certain terminal locations. 

TRSAs are depicted on sectional aeronautical charts and 

listed in the A/FD. The purpose of this service is to provide 

separation between all participating VFR aircraft and all IFR 

aircraft operating within the TRSA. Class C service provides 

approved separation between IFR and VFR aircraft, and 
13-16

Figure 13-20. Vortex generation.

TRACK TRACK

Traffic information would be issued to the pilot of aircraft “A” 

as 12 o’clock. The actual position of the traffic as seen by 

the pilot of aircraft “A” would be 1 o’clock. Traffic information 

issued to aircraft “B” would also be given as 12 o’clock, but 

in this case the pilot of “B” would see traffic at 10 o’clock.

Wind

Figure 13-19. Traffic advisories.

control authority of the encountering aircraft. Also, the 

turbulence generated within the vortices can damage aircraft 

components and equipment if encountered at close range. For 

this reason, a pilot must envision the location of the vortex 

wake and adjust the flightpath accordingly.

During ground operations and during takeoff, jet engine 

blast (thrust stream turbulence) can cause damage and upset 

smaller aircraft at close range. For this reason, pilots of small 

aircraft should consider the effects of jet-engine blast and 

maintain adequate separation. Also, pilots of larger aircraft 

should consider the effects of their aircraft’s jet-engine blast 

on other aircraft and equipment on the ground.

Vortex Generation

Lift is generated by the creation of a pressure differential over 

the wing surface. The lowest pressure occurs over the upper 

wing surface, and the highest pressure under the wing. This 

pressure differential triggers the rollup of the airflow aft of 

the wing resulting in swirling air masses trailing downstream 

of the wingtips. After the rollup is completed, the wake 

consists of two counter rotating cylindrical vortices. Most of 

the energy is within a few feet of the center of each vortex, 

but pilots should avoid a region within about 100 feet of the 

vortex core. [Figure 13-20]

Vortex Strength

The strength of the vortex is governed by the weight, speed, 

and shape of the wing of the generating aircraft. The vortex 

characteristics of any given aircraft can also be changed by the 

extension of flaps or other wing configuration devices as well 

as by a change in speed. The greatest vortex strength occurs 

when the generating aircraft is heavy, clean, and slow.

Vortex Behavior

Trailing vortices have certain behavioral characteristics 

that can help a pilot visualize the wake location and take 

avoidance precautions.

Vortices are generated from the moment an aircraft leaves the 

ground (until it touches down), since trailing vortices are the 

byproduct of wing lift. [Figure 13-21] The vortex circulation 

is outward, upward, and around the wingtips when viewed 

from either ahead or behind the aircraft. Tests have shown 

that vortices remain spaced a bit less than a wingspan apart, 

drifting with the wind, at altitudes greater than a wingspan from 

the ground. Tests have also shown that the vortices sink at a 

rate of several hundred feet per minute, slowing their descent 

and diminishing in strength with time and distance behind the 

generating aircraft.
13-17

25

Wake ends

Wake begins

Rotation Touchdown

Figure 13-21. Vortex behavior.

When the vortices of larger aircraft sink close to the ground 

(within 100 to 200 feet), they tend to move laterally over 

the ground at a speed of 2–3 knots. A crosswind decreases 

the lateral movement of the upwind vortex and increases the 

movement of the downwind vortex. A tailwind condition can 

move the vortices of the preceding aircraft forward into the 

touchdown zone.

Vortex Avoidance Procedures

• Landing behind a larger aircraft on the same runway—

stay at or above the larger aircraft’s approach 

flightpath and land beyond its touchdown point.

• Landing behind a larger aircraft on a parallel runway 

closer than 2,500 feet—consider the possibility of drift 

and stay at or above the larger aircraft’s final approach 

flightpath and note its touch down point.

• Landing behind a larger aircraft on crossing runway—

cross above the larger aircraft’s flightpath. 

• Landing behind a departing aircraft on the same 

runway—land prior to the departing aircraft’s rotating 

point.

• Landing behind a larger aircraft on a crossing 

runway—note the aircraft’s rotation point and, if that 

point is past the intersection, continue and land prior 

to the intersection. If the larger aircraft rotates prior 

to the intersection, avoid flight below its flightpath. 

Abandon the approach unless a landing is ensured 

well before reaching the intersection.

• Departing behind a large aircraft—rotate prior to the 

large aircraft’s rotation point and climb above its climb 

path until turning clear of the wake.

• For intersection takeoffs on the same runway—be 

alert to adjacent larger aircraft operations, particularly 

upwind of the runway of intended use. If an intersection 

takeoff clearance is received, avoid headings that cross 

below the larger aircraft’s path.

• If departing or landing after a large aircraft executing 

a low approach, missed approach, or touch and go 

landing (since vortices settle and move laterally 

near the ground, the vortex hazard may exist along 

the runway and in the flightpath, particularly in a 

quartering tailwind), it is prudent to wait at least 2 

minutes prior to a takeoff or landing.

• En route it is advisable to avoid a path below and 

behind a large aircraft, and if a large aircraft is 

observed above on the same track, change the aircraft 

position laterally and preferably upwind.

Collision Avoidance

14 CFR part 91 has established right-of-way rules, minimum 

safe altitudes, and VFR cruising altitudes to enhance flight 

safety. The pilot can contribute to collision avoidance by 

being alert and scanning for other aircraft. This is particularly 

important in the vicinity of an airport.

Effective scanning is accomplished with a series of short, 

regularly spaced eye movements that bring successive areas 

of the sky into the central visual field. Each movement 

should not exceed 10°, and each should be observed for at 

least 1 second to enable detection. Although back and forth 

eye movements seem preferred by most pilots, each pilot 

should develop a scanning pattern that is most comfortable 

and then adhere to it to assure optimum scanning. Even if 

entitled to the right-of-way, a pilot should yield if another 

aircraft seems too close.
13-18

Clearing Procedures

The following procedures and considerations should assist a 

pilot in collision avoidance under various situations.

• Before takeoff—prior to taxiing onto a runway or 

landing area in preparation for takeoff, pilots should 

scan the approach area for possible landing traffic, 

executing appropriate maneuvers to provide a clear 

view of the approach areas.

• Climbs and descents—during climbs and descents 

in flight conditions which permit visual detection of 

other traffic, pilots should execute gentle banks left 

and right at a frequency which permits continuous 

visual scanning of the airspace.

• Straight and level—during sustained periods of straightand-level flight, a pilot should execute appropriate 

clearing procedures at periodic intervals.

• Traffic patterns—entries into traffic patterns while 

descending should be avoided.

• Traffic at VOR sites—due to converging traffic, 

sustained vigilance should be maintained in the 

vicinity of VORs and intersections.

• Training operations—vigilance should be maintained 

and clearing turns should be made prior to a practice 

maneuver. During instruction, the pilot should be 

asked to verbalize the clearing procedures (call out 

“clear left, right, above, and below”).

High-wing and low-wing aircraft have their respective blind 

spots. The pilot of a high-wing aircraft should momentarily 

raise the wing in the direction of the intended turn and look 

for traffic prior to commencing the turn. The pilot of a lowwing aircraft should momentarily lower the wing and look 

for traffic prior to commencing the turn.

Runway Incursion Avoidance

A runway incursion is “any occurrence in the airport runway 

environment involving an aircraft, vehicle, person, or object 

on the ground that creates a collision hazard or results in a loss 

of required separation with an aircraft taking off, intending 

to take off, landing, or intending to land.” It is important 

to give the same attention to operating on the surface as in 

other phases of flights. Proper planning can prevent runway 

incursions and the possibility of a ground collision. A pilot 

should be aware of the aircraft’s position on the surface at all 

times and be aware of other aircraft and vehicle operations 

on the airport. At times towered airports can be busy and taxi 

instructions complex. In this situation it may be advisable 

to write down taxi instructions. The following are some 

practices to help prevent a runway incursion:

• Read back all runway crossing and/or hold 

instructions.

• Review airport layouts as part of preflight planning, 

before descending to land and while taxiing, as 

needed.

• Know airport signage.

• Review NOTAM for information on runway/taxiway 

closures and construction areas.

• Request progressive taxi instructions from ATC when 

unsure of the taxi route.

• Check for traffic before crossing any runway hold line 

and before entering a taxiway.

• Turn on aircraft lights and the rotating beacon or strobe 

lights while taxing.

• When landing, clear the active runway as soon as 

possible, then wait for taxi instructions before further 

movement.

• Study and use proper phraseology in order to understand 

and respond to ground control instructions. 

• Write down complex taxi instructions at unfamiliar 

airports.

For more detailed information, contact the FAA’s Office 

of Runway Safety and Operational Services web site at 

http://www.faa.gov/runwaysafety/ or visit http://www.aopa.

org/asf/accident_data/incursions.html to access a learning 

tool developed by the FAA and the Aircraft Owners and 

Pilots Association (AOPA) to help pilots and maintenance 

technicians avoid runway incursions involving taxiing 

aircraft. Additional information can also be found in Advisory 

Circular (AC) 91-73, Part 91, Pilot and Flightcrew Procedures 

During Taxi Operations, and Part 135, Single-Pilot Procedures 

During Taxi Operations. 

Chapter Summary

This chapter focused on airport operations both in the air and 

on the surface. For specific information about an unfamiliar 

airport, consult the A/FD and NOTAMS before flying. For 

further information regarding procedures discussed in this 

chapter, refer to 14 CFR part 91 and the AIM. By adhering 

to established procedures, both airport operations and safety 

are enhanced.