Chapter 5: Communications and Flight Information (Notes)

Section A: Radar and ATC Services

  • Overview and history

    • ATC origins: 1930s with teletype, wall-sized blackboards, large maps, and markers representing airplanes. Controllers moved markers to estimate aircraft positions.
    • Radar development: WWII era enabled surveillance of traffic; later adapted to control aircraft taxiing at airports in low visibility.
    • Radar plus computers and transponders markedly increased ATC effectiveness and capacity.

  • Radar fundamentals

    • Radar = synchronized transmitter and receiver that emit radio waves and process reflections for display.
    • Primary radar (ground-based) uses a narrow beam from a rotating antenna; reflections from aircraft appear as echoes (blips) on a radarscope.
    • Radarscope display basics:
    • Electron sweep (CRT) rotates with the antenna.
    • A blip appears when the return echo is intensified at the aircraft's range/position.
    • Range determination: based on two-way travel time of radio waves
    • Speed of radio waves (speed of light): c=186,000 miles/secondc = 186{,}000\ \text{miles/second}
    • Two-way travel time t gives range: R=c⋅t2R = \frac{c\cdot t}{2}
    • Azimuth: angle of the aircraft from the radar site, measured clockwise from north in a horizontal plane, determined by antenna position when echo is received.

  • Limitations of primary radar

    • Anomalous propagation: bending of radar pulses due to atmospheric inversions.
    • Ground clutter: extraneous returns when beam is bent toward the ground, especially in adverse weather.
    • Limitations: difficulty identifying a specific aircraft return; cannot easily display altitude from primary radar alone.

  • Secondary radar (ATCRBS) and components

    • ATCRBS (secondary surveillance radar) overcomes many primary radar limitations.
    • Three ground components in addition to primary radar:
    • Decoder: assigns a discrete transponder code to the aircraft and receives Mode C altitude information.
    • Interrogator: ground system that prompts transponder replies.
    • Transponder: onboard unit that replies with a coded signal.
    • Transponder replies are combined with primary returns and displayed together on the radarscope.
    • Transponder basics:
    • Typical transponder codes can encode up to 4{,}096 values: 4,096=2124{,}096 = 2^{12}
    • The code is often referred to as a “squawk” by ATC.
    • Mode C provides automatic altitude encoding.
    • The IDENT function briefly highlights your aircraft on the radar display to help ATC establish positive contact.
    • Testing and regulations
    • Transponder must be tested/inspected every 24 calendar months for operations in controlled airspace.

  • Transponder operation and phraseology

    • Function selector positions usually include: OFF, SBY (STANDBY), ON, ALT (ALTITUDE), TST (TEST).
    • You may set any 4-digit code from 0000 to 7777 (giving 4,096 total codes).
    • Squawk and Ident
    • ATC assigns a discrete transponder code (squawk code) and may instruct you to press IDENT to aid radar contact.
    • Altitude reporting
    • ALT: activates automatic altitude reporting (Mode C).
    • Common codes (to avoid accidental use):
    • 7500 hijack; 7600 radio failure; 7700 general emergency.
    • Operational notes
    • STANDBY: transponder warmed up and ready but not replying to interrogations.
    • Stop Altitude Squawk: disable automatic altitude reporting.
    • Squawk Altitude: enable automatic altitude reporting.
    • Squawk 1200 is standard for VFR (in many areas).
    • Typical phrases and actions
    • “Squawk (Number) and Ident”: set the given code and press IDENT.
    • “Squawk VFR”: set 1200 for VFR operations (or other code as assigned).
    • “Stop Squawk”: turn the transponder OFF.
    • Operational cautions
    • Do not set 7500, 7600, or 7700 during routine code changes; inadvertent selection can trigger false alarms.
    • Before taxi/flight, ensure the transponder is in an appropriate mode (e.g., STANDBY before taxi, ALTITUDE if Mode C is available).

  • Transponder and ATC procedures in controlled airspace

    • Before taxiing: set transponder to STANDBY; for VFR, use code 1200 unless assigned otherwise.
    • Prior to takeoff in Class C airspace, switch to ALTITUDE (if Mode C is available) as late as practical; otherwise, ON.
    • Initial contact example: announce altitude to nearest 100 feet when calling ATC.
    • If ATC assigns a discrete code, squawk it and say “ident” when instructed.
    • After landing: switch transponder to OFF or STANDBY as soon as practical.
    • Altitude discrepancies: if your reported altitude differs from ATC’s radar readout, ATC may instruct you to stop altitude squawk or adjust as needed; verify altimeter setting if Mode C readout is invalid.

  • ATC radar systems and facilities

    • FAA operates two basic radar systems: Airport Surveillance Radar (ASR) and Air Route Surveillance Radar (ARSR).

    • Both use primary and secondary radar returns plus computers to enhance data such as speed and altitude.

    • Airport Surveillance Radar (ASR)

    • Short-range coverage in the airport vicinity; used for IFR terminal control by Approach/Departure.

    • Often integrated with automated radar terminal system (ARTS).

    • ARTS configurations vary (e.g., ARTS-IIIA) and can detect primary and secondary radar returns; displays aircraft position, altitude, groundspeed, etc.

    • ARTS data helps eliminate dependence on voice communication for altitude and position readouts.

    • Terminal radar approach control facilities (TRACONs)

    • Provide radar and nonradar services at major airports; ensure safe separation during transitions from departure to cruise and from cruise to approach.

    • Long-range ARSR and ARTCCs

    • ARSR: long-range radar; can monitor aircraft within roughly a 200-mile radius (some sites up to 600 miles with remote receivers).

    • ARTCCs: Air Route Traffic Control Centers; coordinate IFR traffic nationwide; provide advisories and vectors upon workload and capability.

    • ARTS-based displays give continuous position/altitude/groundspeed information; most users require Mode C transponder and altitude-encoding altimeter for best results.

    • Radar information integrity and benefits

    • Direct altitude readouts from ARTS reduce verbal communications needs and increase airspace capacity.

  • Special radar topics and concepts

    • VFR Radar Traffic Information Service (Radar Traffic Information Service)

    • ATC routinely provides traffic information to IFR flights; VFR pilots may request radar advisory service (flight following).

    • The service is advisory and not a substitute for collision avoidance; pilot remains responsible for seeing and avoiding other aircraft.

    • Clock reference used by controllers when describing traffic (e.g., 11 o’clock means roughly 30° left of the nose).

    • Traffic info may be limited by radar coverage, controller workload, or frequency congestion; not universally available in all radar sectors.

    • Weather and ground clutter mitigation

    • Moving Target Indicators (MTIs) and Moving Target Detectors (MTDs) eliminate slow-moving and stationary objects from radar returns to reduce clutter.

  • Safety concepts and alerts

    • Controlled Flight Into Terrain (CFIT): aircraft unintentionally flies into terrain/water; often due to lack of situational awareness.
    • Example: Hawker HS-125 crash near Otay Mountain (1981–1991 timeframe) illustrating CFIT risk due to unfamiliarity with terrain and lack of IFR clearance.
    • Safety Alerts: ATC can issue safety alerts for terrain/obstructions or other aircraft; ARTS can support Minimum Safe Altitude Warning (MSAW) monitoring if aircraft is Mode C equipped.
    • VFR safety considerations: radar services increase safety when used fully, but pilots must maintain situational awareness and thoroughly study terrain using aeronautical charts and AFD/Flight Information publications.

  • ATIS, FSS, and information services

    • Automatic Terminal Information Service (ATIS)
    • Pre-recorded, continuously broadcast airport information in high-activity terminal areas; updated when weather or airport conditions change.
    • Broadcasts labeled with successive phonetic letters (Information Alpha, Information Bravo, etc.).
    • At large airports, there may be separate ATIS frequencies for arrivals and departures.
    • Flight Service Stations (FSS)
    • Provide weather briefings, enroute communications, SAR assistance, NOTAMs, and help with flight plans and navigation aid.
    • FSS can assist with VHF Direction Finding (VHF/DF) for locating lost aircraft; requires operable VHF transmitter/receiver.
    • FSS DF services rely on VHF signals and may be listed in Airport/Facility Directory with DF capability.
    • VHF/DF (direction finding)
    • Used by FSS and some towers to locate an aircraft; requires a working VHF transmitter and receiver.
    • ATC facility contacts and procedures
    • Initial contact to ATC should include facility name, aircraft identification, and the type of message or service requested.
    • When talking with ATC, keep communications concise and clear; read back clearances to confirm understanding.

  • Terminology and key concepts

    • ARTS: Automated Radar Terminal System; provides continuous display of aircraft data.
    • ARSR: Air Route Surveillance Radar; long-range radar system.
    • ASR: Airport Surveillance Radar; short-range airport-area radar.
    • TRACON: Terminal Radar Approach Control; manages traffic in terminal areas.
    • NOTAM: Notices to Airmen (D for distant, L for local, FDC for regulatory/chart updates).
    • NTAP: Notices to Airmen Publication; compiles NOTAM(D)s and FDC NOTAMs.
    • A/FD: Airport/Facility Directory; official airport information including runways, services, frequencies, and more.
    • AIM: Aeronautical Information Manual; official guide to basic flight information and ATC procedures.
    • CTAF: Common Traffic Advisory Frequency; non-towered airport advisory frequency.
    • UNICOM/MULTICOM: Advisory communications for non-towered/unattended airports.
    • GCO: Ground Communications Outlet; ground-to-telephone connection for ATC/FSS.
    • LAA: Local Airport Advisory.
    • MSAW: Minimum Safe Altitude Warning; ARTS/ATC function to warn about unsafe altitudes.
    • 5 C’s: climb, communicate, confess, comply, conserve (emergency guidance).
    • ELT: Emergency Locator Transmitter; transmits on 121.5 MHz (VHF) and 243.0 MHz (UHF); battery life and testing requirements apply.

  • Section A summary checklist (highlights)

    • Radar basics recap: primary vs secondary radar; time-of-flight for range; azimuth from rotating beam.
    • Primary radar limitations and secondary radar enhancement via ATCRBS (decoder, interrogator, transponder) providing Mode C altitude.
    • Transponder rules: 24-month testing; codes (0–7 digits per digit; total 4,096 possibilities); common squawks (7500, 7600, 7700).
    • ARTS/ARSR/TRACON/ARTCC roles; airspace coverage and the purpose of TRACONs and ARTCCs.
    • VFR radar advisory service: use of clock references; limitations and responsibilities of pilots.
    • CFIT, safety alerts, and terrain awareness in radar environments.
    • ATIS and FSS as major sources of current airport/weather information; NOTAMs and NTAP as flight information updates.
    • Practical notes on time conversions and UTC (Zulu time) usage for flight planning and ATC communications.

Section B: Radio Procedures

  • VHF communications basics

    • VHF radio band for aviation: 118.0 MHz to 135.975 MHz.
    • Channel spacing and channel count
    • 360-channel radios use 50 kHz spacing: e.g., 118.05, 118.10, 118.15, 118.20, …
    • 720-channel radios use 25 kHz spacing (more channels): e.g., 118.025, 118.050, 118.075, 118.100, …
    • Transceivers combine transmitter and receiver; changing frequencies via the frequency selector; the pull-to-select knob can adjust fractions such as .025 MHz.
    • Squelch control: determines how strong a received signal must be to hear audio; higher squelch reduces noise but can miss weak signals.
    • Volume control and audio listening techniques; if no one is talking, adjust squelch to minimize background noise.

  • Phonetic alphabet and numbers

    • English ICAO phonetic alphabet is standard for international radiotelephony; used to spell difficult words and letters (example: Cessna 649SP → “Cessna Six Four Nine Sierra Papa”).
    • When transmitting numbers, say digits clearly; the number 9 is spoken as "niner" to avoid confusion with German "nein".
    • Decimal points in frequencies are spoken as “point”; decimal point in altimeter settings is omitted when spoken as a number.

  • Time formats and UTC (Zulu time)

    • Aviation uses a 24-hour clock and Coordinated Universal Time (UTC), also called Zulu time.
    • Time conversion rule (illustrative): add or subtract hours depending on time zone differences; expression examples are provided in training materials (e.g., Eastern to Central, etc.).
    • Example conversion shown in training materials; pilots must convert local time to UTC when filing/reading times for flight planning and ATC communications.

  • Common radio procedures and terminology

    • Initial callups include facility name, aircraft ID, and the requested service or message type; example: “Centennial Tower, Cessna 6319 Lima, flight of two.”
    • Use of two-way comms: if you cannot hear the other party, troubleshoot audio, frequency, or mic hardware.
    • If out of range or hardware failure: follow lost communication procedures (Section C) and use light signals if necessary.
    • Transmitter/receiver failure procedures:
    • If you lose comms, remain outside controlled airspace until you can re-establish comms or contact ground facilities by other means.

  • VHF communications: practical handling

    • To avoid frequency congestion, keep transmissions concise; include who you are, where you are, and what service you request.
    • When communicating with ATC at controlled fields, you may be asked to stand by; controllers will respond when ready.
    • When changing frequencies during handoffs, verify the new frequency via readback from ATC (e.g., “Cessna 58 Romeo, roger, contact tower 118.3”).
    • In busy Class B/C airspaces, pilots may be handed off between controllers and frequencies; ensure correct readbacks to confirm handoffs.

  • Formation flying communications (special case)

    • Formation flights use 122.75 MHz for air-to-air communications; lead is responsible for traffic avoidance, navigation, and ATC communications.
    • Initial call example for a formation: “Centennial Tower, Cessna 6319 Lima, flight of two.”
    • If radios fail, stay outside Class D airspace until traffic direction is determined; rely on light signals from the tower for guidance.
    • Daytime acknowledgement: rock wings; nighttime: blink lights to acknowledge signals.

  • Radio failure and emergency procedures (MAYDAY/PAN-PAN)

    • Emergency (MAYDAY) and urgency (PAN-PAN) calls have priority over other communications.
    • In distress, use MAYDAY three times; provide exact location, nature of emergency, and required assistance.
    • In an urgency state, PAN-PAN is used with priority to notify others of the situation.

  • ELTs (Emergency Locator Transmitters)

    • ELTs transmit on 121.5 MHz (VHF) and 243.0 MHz (UHF); battery life and testing requirements apply.
    • If ARTS radar is in use and the aircraft is in distress, squawk 7700 to alert ATC and assist SAR coordination.
    • ELT battery replacement/recharge requirements: battery must be replaced or recharged after half-life or after cumulative use of one hour.
    • ELT testing rules: test in a screened room when possible; otherwise limit testing to the first five minutes after the hour and no more than three audible sweeps; airborne tests are not allowed.

  • Lost communication procedures (Class D example)

    • If radio is inoperative, follow established lost communication procedures and use 7600 squawk code to indicate radio failure to ATC.
    • In some cases, it may be best to land at an alternate airport with functioning communications.

  • Section B summary checklist (highlights)

    • VHF radio range and channel spacing; proper use of 360-channel vs 720-channel radios.
    • Correct use of squelch and volume; how to adjust for clear reception.
    • Phonetic alphabet usage and number pronunciation to avoid confusion.
    • UTC/Zulu time and 24-hour clock usage for planning and ATC communication.
    • CTAF, UNICOM, MULTICOM usage for uncontrolled airports; GCO for ATC/FSS connections.
    • Initial callups, frequency handoffs, and readbacks; procedures for in-flight radio failures and distress calls.
    • Five C’s for lost situational awareness: climb, communicate, confess, comply, conserve.
    • ELTs: operational basics, testing rules, and SAR coordination.

Section C: Sources of Flight Information

  • Airport/Facility Directory (A/FD)

    • Published by the National Aeronautical Charting Office (NACO); descriptive listings for all public airports, heliports, and seaplane bases.
    • Seven regional volumes; reissued every 56 days; used with aeronautical charts.
    • Directory legend explains items in airport listings.
    • Listings include: runways, communication/navigation facilities, weather data sources, airspace, and airport services; includes radar service availability and communications frequencies.
    • Notable: the designation “Rgt tfc” indicates right-hand traffic patterns.

  • NOTAMs and NOTAM-related publications

    • NOTAM(D): distant NOTAMs for navigational facilities, public-use airports, seaplane bases, and heliports.
    • NOTAM(L): local NOTAMs (taxiway closures, runway crossings, outages near runways, etc.).
    • FDC NOTAMs: regulatory information such as temporary flight restrictions or amendments to instrument procedures.
    • NTAP: Notices to Airmen Publication; compiled NOTAM(D)s and FDC NOTAMs; issued every 28 days.

  • Advisory Circulars (ACs) and advisory information services

    • Advisory Circulars provide nonregulatory guidance and methods for complying with FARs; not binding unless incorporated by regulation.
    • Jeppesen Information Services offer revisions for government publications (FAR/AIM, J-AID, etc.) and updates to aviation materials.
    • The FAR service is a subscription that provides updates to commonly used FAR parts.

  • Aeronautical Information Manual (AIM)

    • The official guide to basic flight information and ATC procedures; describes the national airspace system, ATC facilities and services, and radio phraseology.
    • Chapters listed indicate where to find information on navigation aids, airspace, radar services, air traffic procedures, safety, and pilot/controller glossary.

  • Other electronic/publication sources

    • FAA Internet resources: FAA Home Page and related links (e.g., FedWorld) for ordering ACs, FARs, and other government publications.
    • Electronic Flight Publications provide access to flight information via modem/computer and the Internet.

  • Section C summary checklist (highlights)

    • A/FD as the primary source for airport data, services, and frequencies.
    • NOTAMs (D, L, FDC) provide timely flight information; NTAP compiles NOTAMs.
    • AIM as the official guide to ATC procedures, airspace, and pilot/controller communications.
    • Advisory Circulars provide nonregulatory guidance and explanations for FARs.
    • Jeppesen and other commercial services supplement government publications for pilots.
    • The FAA also distributes aviation information via the Internet and electronic services.

Part III: Aviation Weather (introductory note)

  • Weather: a major variable affecting flight safety and planning. The portion provided introduces Part III, which covers weather forms, forecasts, and meteorology concepts used by pilots. It emphasizes understanding how weather forms and forecasts influence flight operations and safety.

  • Key takeaways related to weather information (to be explored in Part III)

    • Weather significantly impacts flight planning and execution.
    • Pilots should learn how meteorologists forecast weather and how forecasts are presented to pilots.
    • The AIM and NOTAM system also interface with weather information to support safe flight planning.

Connection to previous lectures and real-world relevance

  • The radar and ATC sections establish how modern airspace is managed: surveillance (primary and secondary radar), data links with transponders, and the role of ARTS/TRACON/ARTCC in sequencing and separation.
  • Radio procedures emphasize clear, concise, standardized communication (phonetic alphabet, proper call signs, readbacks) to maintain safety and efficiency in a crowded airspace.
  • NOTAMs, A/FD, AIM, and advisory publications provide pilots with the essential reference framework used in day-to-day flight planning and operations, including how to obtain weather and airport information, and how to stay compliant with FARs.
  • Safety culture is highlighted through CFIT awareness, ATIS, MSAW, and emergency procedures (MAYDAY vs PAN-PAN, ELTs).
  • Practical examples and questions included throughout (e.g., ATC phraseology, transponder codes, and CTAF procedures) reinforce the application of concepts in real-world flight.

Key numerical references and formulas

  • Speed of light (radio waves): c=186,000 miles/sc = 186{,}000\ \text{miles/s}
  • Radar frequency example: ASR-9 frequency around f=2.7×109 Hz=2.7 GHzf = 2.7 \times 10^9 \text{ Hz} = 2.7 \text{ GHz}
  • Transponder code capacity: up to 4,096=2124{,}096 = 2^{12} distinct codes
  • Transponder coding guidance and common emergency codes: 7500 (hijack), 7600 (radio failure), 7700 (emergency)
  • Time systems: 24-hour clock; Coordinated Universal Time (UTC, Zulu time); conversion rules illustrated in the training material (e.g., Eastern to Central, and cross-time-zone flight planning)
  • NOTAMs and NOTAM formats; NTAP updates every 28 days

Notes on figures and figures-based references

  • Numerous figures (5-1 through 5-40, etc.) illustrate radar schematics, ARTS displays, and ATC procedures. Use these as visual anchors when reviewing concepts such as radar display, transponder operation, and ATIS/CTAF interactions.

Practical study tips for the exam

  • Be able to explain the difference between primary radar and ATCRBS secondary radar, and describe the three ground components of the secondary radar system (decoder, interrogator, transponder).
  • Memorize the essential transponder codes (7500, 7600, 7700) and their meanings; know the requirement for 24-month transponder inspection.
  • Understand ARSR vs ASR vs TRACON roles and how they fit into the national airspace structure.
  • Be able to describe VFR radar advisory service, including how traffic is referenced (clock positions) and its limitations.
  • Know ATIS purpose, lettering convention (Information Alpha, Bravo, etc.), and how ATIS interacts with flight planning.
  • Be familiar with NOTAM types and the NTAP cycle, plus the role of A/FD in flight planning.
  • Understand the basics of radio procedures, including frequency changes, readbacks, and lost communication procedures.

End of notes for Chapter 5 (Section A–C) and intro to Part III: Aviation Weather

  • Part III begins with a focus on weather, meteorology for pilots, forecast graphics, and dissemination of weather information to pilots. Further study will cover detailed weather theory, METARs, TAFs, and weather-related decision making.