Stage 2 Lesson 10

Navigation/Communication Equipment

Equipment used by pilots to communicate with Air Traffic Control (ATC) and navigate the aircraft using radio frequencies and onboard avionics systems.

What frequency range do civilian pilots use to communicate with ATC?

Between 118.000 MHz and 136.975 MHz in the Very High Frequency (VHF) range.

What spacing is required to use the full ATC system?

25 kHz spacing (e.g., 134.500, 134.525, 134.550).
If a frequency can’t be selected, ask ATC for an alternate

What is simplex operation in aviation radios?

Transmitting on 122.1 MHz (COM radio) and receiving on a VOR frequency (NAV radio).
Allows communication with Flight Service Stations (FSS).

What does the audio panel allow a pilot to do?

• Adjust volume for selected receivers

• Choose which transmitter to use

• Select between cabin speaker and headphones
  (Some panels have an OFF position between the two.)

Why is a headset with a boom microphone recommended for communication?

• Reduces distraction compared to handheld mics

• Clearer transmissions (mic close to lips)

• Minimizes ambient cockpit noise interference

What happens when switching between COM1 and COM2?

• Changes both transmitter and receiver frequencies

• Useful when monitoring one frequency while transmitting on another, e.g.:

  • Listening to ATIS while talking to ATC

  • Monitoring a navigation signal for ID

What features does a combined GPS/Comm radio provide?

• Contains both a GPS receiver and communication transceiver

• Can determine airspace crossings or fixes

• Automatically selects the appropriate ATC frequency based on location

What is Radar and Transponders

Radar is a system that detects and tracks aircraft using radio waves.
A transponder (transmitter + responder) is an aircraft-mounted device that automatically replies to radar interrogations from Air Traffic Control (ATC), allowing precise identification and tracking.

What are primary radar returns and their limitation?

• Primary returns are radar signals reflected from an aircraft’s metallic structure.

• They provide only position, not identification or altitude, and are limited in range and accuracy.

What are secondary radar returns, and why are they important?

• Secondary returns come from transponder replies to ground interrogations.

• They allow automation and provide aircraft identification and altitude information, improving ATC efficiency.

What happens when a pilot presses the Ident button?

• The aircraft’s radar return is intensified on the controller’s screen for quick identification.

• Used only when requested by ATC.

• Pilots should verbally confirm when changing codes or pressing Ident.

How does an aircraft transponder operate?

• Receives interrogation signals from ATC radar.

• Sends a coded reply back to the radar station.

• Reply is displayed on the controller’s screen.

• A reply light on the transponder flickers with each transmission.

Who assigns transponder codes and what are they used for?

• Assigned by ATC to identify aircraft on radar.

• Each code corresponds to a specific flight for tracking and communication.

What is a Mode C (Altitude Reporting)

Mode C is a transponder function that automatically reports an aircraft’s pressure altitude to Air Traffic Control (ATC), allowing controllers to see both position and altitude on radar displays.

What information does primary radar show compared to secondary radar?

• Primary radar: Displays range and bearing only.

• Secondary radar: Can display altitude (Mode C) if the aircraft has an encoding altimeter or blind encoder.

What happens when the transponder is set to the ALT position?

• The aircraft’s pressure altitude is transmitted to ATC.

• The altitude is based on 29.92 in. Hg, not the aircraft’s local altimeter setting.

• Changing the Kollsman window does not affect the altitude reported to ATC.

When must a transponder be ON and reporting altitude?

• Must be ON at all times when operating in controlled airspace.

• Altitude reporting (Mode C) is required:

  • In Class B and Class C airspace

  • Within a 30-mile radius of the primary airport in Class B airspace

• Should be ON at all times even outside those areas for safety.

What is Communication Procedures? 

in aviation ensure clear, standardized exchanges between pilots and Air Traffic Control (ATC) to maintain safety, efficiency, and understanding during all phases of flight—especially under instrument flight rules (IFR).

Why is clarity in communication essential for instrument flight?

• Prevents misunderstanding between pilots and ATC.

• Ensures accurate execution of clearances and instructions.

• Promotes safety and efficiency during IFR operations.

What is the Pilot/Controller Glossary and where is it found?

• Found in the Aeronautical Information Manual (AIM).

• Provides standardized aviation terms and definitions understood by both pilots and controllers.

• Updated twice a year—pilots should review it regularly.

Why is a phonetic pronunciation guide used in aviation communication?

• Ensures clarity when transmitting letters and numbers over the radio.

• Prevents confusion due to similar-sounding words or poor radio quality.

How do controllers maintain standard communication procedures?

• Follow the Air Traffic Control Manual, which provides specific phrasing and terminology for various situations.

• Creates predictable, consistent communication patterns for pilots.

How can pilots improve their communication with ATC?

• Study AIM communication examples.

• Listen to other pilots to learn effective phrasing.

• Use plain English if clarification is needed.

• Always ask for clarification if uncertain.

• Maintain professionalism and cooperation with ATC.

What is key to ensuring a safe instrument flight in terms of communication?

• Cooperation between pilot and controller.

• Mutual understanding and clear, standardized communication practices.

What are Communication Facilities?

The various Air Traffic Control (ATC) units and services that work together to manage and separate aircraft operating under Instrument Flight Rules (IFR).

What is the controller’s primary responsibility under IFR?

Separation of aircraft operating under Instrument Flight Rules (IFR) to ensure safety and orderly traffic flow.

What are the main ATC facilities used to provide communication and control for IFR flights?

• Flight Service Station (FSS): Provides pilot briefings, flight plan filing, weather info, and en route assistance.

• Airport Traffic Control Tower (ATCT): Manages takeoffs, landings, and ground movements at controlled airports.

• Terminal Radar Approach Control (TRACON): Handles arriving and departing traffic within terminal areas (typically 30–50 miles from major airports).

• Air Route Traffic Control Center (ARTCC): Manages en route aircraft between terminal areas across large regions.

What is Flight Service Stations (FSS)

ATC facilities that provide essential preflight and en route services to pilots, such as weather briefings, flight plan handling, and communication relay between pilots and other ATC units.

What is usually a pilot’s first contact with ATC?

• Flight Service Station (FSS)—either by radio or telephone.

• FSS provides initial support for flight planning, clearances, and weather information.

What services do Flight Service Stations provide?

• Pilot briefings

• Receive and process flight plans

• Relay ATC clearances

• Originate NOTAMs (Notices to Airmen)

• Broadcast aviation weather

• May also provide:

  • En Route Flight Advisory Service (EFAS)

  • Weather observations

  • Customs and Immigration notifications for international flights

How can pilots contact Flight Service by telephone?

• Dial 1-800-WX-BRIEF (usable anywhere in the U.S.).

• Automatically connects to the nearest FSS based on the caller’s area code.

What are the ways to make radio contact with FSS?

• Direct transmission

• Remote Communication Outlets (RCOs)

• Ground Communication Outlets (GCOs)

• Duplex transmissions via NAVAIDs
  (Best reference: Airport/Facility Directory (A/FD) and sectional chart legend panel.)

How does an FSS process a filed flight plan?

• FSS sends the flight plan to the ARTCC host computer.

• The computer generates flight progress strips for:

  • The tower

  • The departure radar facility

  • The Center controller for the first sector entered

• Strips are sent:

  • ~30 minutes before departure to local facilities

  • ~30 minutes before airspace entry to en route centers

• If the plan is not opened, it times out 2 hours after the proposed departure time.

How does a pilot obtain an IFR clearance when departing from Class G airspace?

• Clearance received via FSS radio or telephone.

• May include:

  • Clearance void time: Must be airborne before this time.

  • Release time: Pilot cannot depart before this time.

• Pilots should report expected airborne time to help ATC coordination.

• Example: If void time is 10 minutes past the hour, taking off exactly at that time means the clearance is void.

• Pilots may request a specific void time when filing their flight plan.

What is ATC Towers?

airport-based facilities responsible for managing ground movements, takeoffs, landings, and airspace immediately surrounding the airport.
They ensure safe coordination of IFR and VFR aircraft operating within Class D airspace and in the airport traffic pattern.

How many controllers are typically involved in handling an instrument flight in the tower?

• Several controllers may be involved.

• Duties are divided among clearance delivery, ground control, and local control positions.

• Each frequency can be found in the A/FD and on instrument approach charts.

What happens if there is no dedicated clearance delivery position?

• The ground controller performs clearance delivery duties.

• At busy airports, pre-taxi clearance is required (frequency in the A/FD).

• Taxi clearance should be requested no more than 10 minutes before proposed taxi time.

What is recommended when receiving an IFR clearance?

• Always read back the clearance to confirm accuracy.

• Clearances follow a predictable format known as C-R-A-F-T:

  • C – Clearance limit (usually destination airport)

  • R – Route (including any DP or airway)

  • A – Altitude (initial assigned altitude)

  • F – Frequency (for departure control)

  • T – Transponder code

What are best practices for copying and confirming clearances?

• Have CRAFT written in advance.

• Make small changes as the controller reads the clearance.

• Develop clearance shorthand to minimize writing time.

• Review and have the departure procedure (DP) available before accepting a clearance.

What should pilots know about Departure Procedures (DP)?

• Must have text or graphic representation of the DP.

• Review it before accepting a clearance.

• If the DP includes an altitude or frequency, those may be omitted from the clearance.

• The latest clearance always supersedes any previous one.

  • Example: If DP says “climb to 2,000 ft” but ATC says “climb to 8,000 ft,” the DP restriction is canceled.

What does “Clearance on request” mean?

• The IFR clearance hasn’t yet been received from the Center computer.

• The controller will contact the pilot when it’s available.

• Pilots can use this time for taxi and pre-takeoff checks.

What are the responsibilities of the local controller?

• Manages operations within Class D airspace and on active runways.

• At IFR towers, may have vectoring authority.

• At VFR towers, cannot provide vectors but can accept IFR arrivals from radar facilities.

• Coordinates local traffic with radar controllers.

How do towers coordinate with radar controllers for airspace usage?

• Although Class D airspace usually extends 2,500 ft above field elevation, towers often release the top 500 ft to radar controllers.

• When vectored over an airport at an altitude that appears to enter tower airspace, no tower contact is required—coordination is handled by ATC.

When can the tower issue a takeoff clearance?

• Only after the departure controller has issued a release.

• The departure radar controller may be in the same building as the tower or remotely located.

What are Terminal Radar Approach Control (TRACON)?

Facilities are terminal ATC units that manage arriving and departing aircraft within terminal airspace, providing the connection between the departure airport and the en route structure of the National Airspace System (NAS).

What is the primary role of TRACON?

• Acts as the link between departure airports and en route ATC.

• Manages arrivals, departures, and overflights in the terminal area.

• Provides radar services for traffic sequencing and separation.

What are the typical dimensions of terminal airspace controlled by TRACON?

• Normally extends 30 nautical miles (NM) from the facility.

• Vertical extent of approximately 10,000 feet.

• Actual dimensions vary by location.

• Class B and C airspace dimensions shown on aeronautical charts.

How is terminal radar airspace organized and addressed?

• Divided into sectors, each with one or more controllers and a discrete frequency.

• All TRACON facilities are approach controls and should be addressed as “Approach” unless directed otherwise (e.g., “Contact departure on 120.4”).

Where are terminal radar antennas located, and what do TRACON controllers use?

• Antennas are typically on or near the airport.

• Controllers use:

  • Airport Surveillance Radar (ASR) for primary radar returns.

  • Automated Radar Terminal System (ARTS) for transponder replies.

• Combined data appears on the controller’s radar scope.

What are Minimum Vectoring Altitudes (MVAs)?

• The lowest altitudes controllers may assign to aircraft for radar vectors.

• Not published or available to pilots; displayed only on controller screens.

• Pilots should query ATC if assigned an altitude that seems too low.

How does TRACON coordinate departures with the control tower?

• When a pilot reports ready for takeoff, the tower contacts TRACON for a release.

• Tower issues takeoff clearance only after TRACON fits the flight into departure flow.

• Pilots may be instructed to “hold for release.”

• Once cleared, departure control expects the aircraft’s call—no need to restate clearance details.

When should the transponder be activated before departure, and why?

• Keep transponder on standby until takeoff clearance is received.

• TRACON’s system automatically initiates tracking when it detects the assigned code after takeoff.

• Aircraft appears as a moving target with a data block (showing ID, type, altitude, and airspeed).

What radar systems do TRACON facilities use, and how do they display weather?

• ASR-3: Displays radar returns but no precipitation intensity levels—controllers rely on pilot reports.

• ASR-9: Displays up to six levels of precipitation intensity.

  • Light: No avoidance required

  • Moderate, heavy, or extreme: Require planning/avoidance

• Temperature between –20°C and +5°C can cause icing, even in light precipitation.

• Higher intensity returns can obscure data blocks; controllers may limit display unless requested.

What should pilots do if uncertain about weather displayed on TRACON radar?

• Ask the controller if the facility can display precipitation intensity levels.

• Small aircraft should avoid levels 3 or higher.

• Always consider both precipitation and temperature for icing potential.

What is Tower En Route Control (TEC)

an ATC program that allows instrument flights to operate entirely within terminal airspace under the control of interconnected tower and TRACON facilities, rather than the en route ARTCC system.

What is the purpose of Tower En Route Control (TEC) routes?

• Allows IFR flights to operate entirely within terminal airspace.

• Used primarily for short-distance IFR flights below 10,000 feet.

• Reduces ARTCC workload by keeping low-altitude, short-range flights in terminal radar control.

Where can pilots find TEC routes and altitude limits?

• Published in the Airport/Facility Directory (A/FD).

• Typically designed for aircraft operating below 10,000 feet.

• Pilots should include “TEC” in the remarks section of their flight plan to indicate participation.

Are pilots limited to the major airports listed in TEC city pairs?

• No. Flights may begin or end at any airport within about 30 NM of the listed city-pair airports.

• Example: A New York (NYC)–Bradley (BDL) TEC route may include destinations such as Hartford (HFD).

What is the Minimum Safe Altitude Warning (MSAW) system?

• An automated safety feature of terminal radar equipment.

• Predicts an aircraft’s position 2 minutes ahead based on its current path.

• Issues a safety alert if the projected path could encounter terrain or obstacles.

• Can be triggered by an unusually rapid descent rate during a nonprecision approach.

What is Air Route Traffic Control Center (ARTCC)?

an ATC facility responsible for maintaining separation of IFR flights in the en route structure, typically covering multiple states and managing high-altitude and low-altitude sectors.

What is the primary function of an ARTCC?

• Maintain separation of IFR flights in the en route NAS structure.

• Track aircraft with Center radars (Air Route Surveillance Radar, ARSR) using transponder returns.

How do ARTCC radars display weather?

• Older radars:

  • Light precipitation: slashes

  • Moderate rainfall: Hs

• Newer radars:

  • Three levels of blue intensity

  • Controllers can select weather intensity to display.

• Note: Higher intensity weather can obscure aircraft data blocks; pilots should not expect ATC to continuously display weather.

How is ARTCC airspace organized?

• Divided into sectors, similar to terminal airspace.

• Most airspace also divided by altitude into high and low sectors.

• Each sector has a dedicated controller team and assigned radio frequencies.

How are ARTCC communications handled?

• ARTCC uses a network of remote transmitter/receiver sites.

• Pilots may hear the same controller on different frequencies when moving between remote sites.

• All ARTCC frequencies are listed in the back of the A/FD and on en route charts.

What does Center approach/Departure Control refer to?

refers to ATC services provided by ARTCC controllers for aircraft departing from or arriving at airports outside terminal radar airspace, including both towered and non-towered airports. These controllers manage IFR traffic and assume terrain/obstacle responsibility only after specific conditions are met.

How do pilots communicate with Center controllers when departing?

• Tower-controlled airport: Tower instructs pilot to contact the appropriate Center.

• Non-towered airport: Clearance includes instructions like “Upon entering controlled airspace, contact [Center] on [frequency].”

• Responsibility: Pilots remain responsible for terrain clearance until reaching the controller’s Minimum Vectoring Altitude (MVA).

When does a Center controller assume responsibility for terrain/obstacle clearance?

• Pilot responsible until above minimum IFR altitude.

• Hearing “Radar contact” alone does not relieve pilot responsibility.

• Controller assumes responsibility when issuing:

  • Heading,

  • Direct route, or

  • “Direct when able.”

• Pilots must check departure airport listings in the A/FD for obstacles if unsure.

What must pilots do if a steeper-than-standard climb gradient is required?

• Controller will advise if needed (e.g., >200 ft per nautical mile).

• Pilots remain responsible for confirming obstacles in the departure path.

• When in doubt, ask the controller for the required gradient.

What does the phrase “when able” mean in a Center clearance?

• Proceed to a waypoint, intersection, or NAVAID as soon as the aircraft can navigate there using onboard systems with proper guidance.

• If flying VFR, pilot retains responsibility for terrain and obstacle clearance.

What are limitations of Center radar for approach/departure?

• 1 NM ≈ 1/28 inch on controller’s scope.

• Distant airports: harder to estimate headings/distances.

• Controllers providing vectors to final set range ≤125 NM for accuracy.

• Expect minimal vectoring at locations far from the radar antenna.

What is ATC Inflight Weather Avoidance Assistnce?

ATC assists IFR pilots in avoiding hazardous weather to the extent possible, using radar-derived precipitation data and pilot reports (PIREPs). Assistance is limited by radar capability, traffic volume, frequency congestion, and controller workload.

How does ATC detect and display weather?

• Sends radio beams; returns indicate precipitation (rain, hail, snow).

• Larger/denser objects = stronger return.

• Intensity measured in dBZ (decibels relative to radar reflectivity factor).

• ATC cannot detect clouds or turbulence.

• Specific precipitation type cannot be determined; all radar returns reported as “precipitation.”

How is precipitation intensity described to pilots?

Intensity	dBZ	Notes
LIGHT	<30	Not used by ARTCC
MODERATE	30–40	Standard
HEAVY	40–50	Standard
EXTREME	>50	Standard

• ARTCC normally uses only MODERATE and HEAVY/EXTREME.

• If radar cannot determine intensity: “INTENSITY UNKNOWN.”

What radar systems do ARTCCs use?

• WARP (Weather and Radar Processor): Mosaic from multiple NEXRAD sites.

  • Precipitation data may be up to 6 minutes old.

• Narrowband ARSR: Displays 2 intensity levels (MODERATE, HEAVY/EXTREME).

How does turbulence relate to ATC radar weather displays?

• Radar cannot detect turbulence.

• Turbulence generally increases with precipitation intensity.

• Severe turbulence can occur near convective activity, even in clear air.

• Thunderstorms: severe or greater turbulence expected.

• Maintain ≥20 miles distance from thunderstorms.

How does ATC assist pilots with weather avoidance?

• riority: separate aircraft & issue safety alerts.

• Assistance depends on: radar limitations, traffic volume, frequency congestion, workload.

• Pilots may request:

  • Course deviation (direction & distance)

  • Altitude change

  • Routing assistance

• IFR pilots must have ATC clearance before deviating, except in emergencies (14 CFR §91.3).

What info should pilots provide when requesting a weather detour?

1. Point where detour begins

2. Proposed route & extent (direction/distance)

3. Point to resume original route

4. Flight conditions (IMC/VMC)

5. Airborne radar capability

6. Any further possible deviations

• Make requests well in advance to help controller accommodate safely.

Why are PIREPs important for ATC?

• Define nature & extent of weather in an area.

• Pilots should report:

  • Turbulence

  • Visibility

  • Cloud tops & bases

  • Hazards: ice, hail, lightning