Air Traffic Control

Traffic pattern

The standard rectangular flight path around an airport for arriving and departing aircraft

Downwind leg

Flight path parallel to the runway, flying opposite the direction of landing

Base leg

Flight path at a right angle to the runway, preparing to turn final

Final approach

Flight path aligned with the runway, descending to land

Crosswind leg

Flight path perpendicular to the runway after takeoff, before turning downwind

Upwind leg

Flight path parallel to the runway, flown after takeoff and before crosswind

Pattern altitude

The recommended altitude (usually 1,000 feet AGL for light aircraft) for flying the traffic pattern

ATC

Air Traffic Control; provides instructions and clearances to ensure safe, orderly, and expeditious flow of air traffic

Towered airport

An airport with an operating control tower; pilots must receive clearances to taxi, take off, and land

Nontowered airport

An airport without a control tower; pilots use common traffic advisory frequency (CTAF) to self-announce positions and intentions

CTAF

Common Traffic Advisory Frequency; used for self-announcing at nontowered airports

UNICOM

A non-government communication facility providing airport information at nontowered airports

Multicom

A frequency (usually 122.9 MHz) used when no UNICOM or CTAF is available

ATIS

Automatic Terminal Information Service; continuous broadcast of recorded airport information (weather, runways, NOTAMs)

Clearance

Authorization from ATC to proceed as requested or instructed

Readback

Repeating an ATC clearance or instruction to confirm understanding

Roger

I have received all of your last transmission

Wilco

Will comply (I will follow your instructions)

Say again

Request to repeat the last transmission

Standby

Wait; I will call you back

Affirmative

Yes

Negative

No

Squawk

Set your transponder to a specific code

Ident

Press the "ident" button on your transponder for ATC to identify you

Light gun signals

Visual signals from the tower to communicate with aircraft when radio communication fails

Red light (steady)

Stop (on ground); Give way, continue circling (in air)

Green light (steady)

Cleared for takeoff (on ground); Cleared to land (in air)

Transponder

Electronic device that responds to ATC radar with aircraft identification and altitude

ADS-B

Automatic Dependent Surveillance–Broadcast; broadcasts aircraft position and information to ATC and other aircraft

Lost comm procedures

If radio fails, remain outside or above traffic pattern, observe traffic, enter pattern, and look for light gun signals

Emergency frequency

121.5 MHz; used for distress and emergency communications

Mayday

Distress call indicating grave and imminent danger; requires immediate assistance

Pan-Pan

Urgency call indicating a problem that is not immediately life-threatening

Class B airspace

Airspace around the busiest airports; requires ATC clearance to enter

Class C airspace

Airspace around airports with a control tower and radar; requires two-way radio communication

Class D airspace

Airspace around airports with a control tower; requires two-way radio communication

Class E airspace

Controlled airspace not classified as A, B, C, or D; no specific communication required for VFR

Class G airspace

Uncontrolled airspace; no ATC services provided

Phraseology

Standardized words and phrases used in aviation communication to avoid confusion

Hold short

Instruction to stop before entering a runway or taxiway

Cleared for the option

ATC clearance allowing a pilot to perform a touch-and-go, stop-and-go, low approach, or full stop landing

Go around

Discontinue approach to landing and climb out for another attempt

Base to final

The turn from base leg to final approach in the traffic pattern

Wake turbulence

Disturbed air left behind an aircraft, especially large or heavy aircraft; avoid by staying above and landing beyond their touchdown point

NOTAM

Notice to Airmen; time-sensitive information about hazards or changes at airports or in airspace

Communicating with ATC

Essential at large airports and busy airspace

ATC radar services

Enhance safety and efficiency for VFR flights

Radar advisories

Traffic advisories and limited vectoring for VFR aircraft

Radar identification

Aircraft must be in radar coverage and communicate with ATC

Controller discretion

Controllers may provide or deny radar assistance based on workload

Radar limitations

Services depend on radar coverage, frequency congestion, and traffic volume

Pilot responsibility

Pilots must always see and avoid other aircraft

Radar vectors

Advisory only; do not authorize violation of regulations

Safety concerns

Pilots must inform ATC if instructions compromise safety

ATIS

Automatic Terminal Information Service; broadcasts weather and airport status

ATIS contents

Includes METAR, instrument approaches, active runways, VFR instructions

ATIS monitoring

Pilots must listen before contacting ATC and report ATIS identifier

Initial contact

Provide aircraft ID, type, location, VFR request, direction, altitude, ATIS

Clearance delivery

May assign altitude, departure frequency, and transponder code

Ground control

Contact when ready to taxi if no clearance delivery

Radar traffic advisories

Request on initial contact with ground control if needed

Departure frequency

Preset before takeoff; tower may not provide after takeoff

Maintain communication

Stay on assigned frequency until instructed to change

Departure control

Provides radar traffic advisories and describes other aircraft by clock position

Clock position

Based on aircraft track, not heading; adjust for wind correction

ARTCC

Air Route Traffic Control Center; handles en route IFR and VFR advisories

Radar automation

Controllers use radar displays with aircraft data and weather overlays

Approach control handoff

Monitor destination ATIS and contact approach control when handed off

Transponder code

Assigned by ATC to identify aircraft on radar

Special squawk codes

7500 (hijacking), 7600 (comm failure), 7700 (emergency), 7777 (military)

Priority alerts

Entering special codes triggers ATC priority alerts

Arrival procedures

Provide ATIS identifier, may get new transponder code or "ident" request

Tower contact

Contact tower for landing clearance when instructed

Shared frequency

Tower and ground may share frequency at less busy airports

ATC familiarity benefits

Enhances situational awareness and safety; valuable for instrument training

ATC facility visits

Pilots encouraged to visit ATC facilities to learn more

Effective ATC communication

Essential for safe and efficient flying in controlled airspace

ADS-B

Automatic Dependent Surveillance-Broadcast; a modern air traffic tracking and management system

ADS-B purpose

Part of the FAA's NextGen initiative to modernize air traffic control (ATC)

ADS-B vs. radar

Provides more accurate, frequent position data and lets pilots see more traffic than radar

Networked environment

Aircraft broadcast their position, not relying on radar site returns

ADS-B position updates

Updates aircraft position about once every second

ADS-B Out

Transmits aircraft position, velocity, and altitude to ATC and other aircraft

ADS-B In

Receives transmissions from ground stations and other aircraft; provides traffic and weather info

ADS-B Out purpose

Required for air traffic management and aircraft separation

ADS-B In benefits

Subscription-free cockpit weather and traffic displays for pilots

ADS-B coverage

Relies on a network of over 700 ground stations in the U.S.; excellent above 3,000 feet AGL

FIS-B

Flight Information Services-Broadcast; provides weather data (NEXRAD, METARs, TAFs, etc.) to pilots

FIS-B cost

No subscription fees; delivered via FAA ground stations to equipped aircraft

FIS-B display options

Weather shown on panel displays or portable devices like iPads

TIS-B

Traffic Information Services-Broadcast; broadcasts traffic location to pilots in equipped aircraft

TIS-B range and accuracy

Custom traffic reports for ADS-B Out aircraft; reliable within about 30 miles

TIS-B without ADS-B Out

Less reliable; not all nearby aircraft shown if not equipped with ADS-B Out

ATC benefits from ADS-B

Allows reduced separation, more direct routing, and coverage in areas with no radar

ADS-B and ground safety

Improves runway safety and traffic management on airport surfaces

Pilot benefits of ADS-B

Access to real-time, no-subscription weather and robust traffic awareness

ADS-B Out requirements

Mandated in airspace where Mode C transponder is required: Class A, B, C, E >10,000 ft MSL, within 30 nm of major airports

ADS-B Out installation

Must be permanently installed and meet FAA performance standards, using WAAS GPS position data

ADS-B In requirement

Optional for pilots; gives safety and situational awareness benefits

Practical tip

Know how ADS-B is installed and operates in aircraft you fly