UA.V.C.K5: Frequency spectrums and associated limitations.

ACS Area V — Operations Task C: Emergency Procedures References: ACAdvisory CircularCloseFAA guidance that explains acceptable ways to comply with rules or understand FAA procedures. 107-2; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-H-8083-25; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-G-8082-22; SAFOsSafety Alert for OperatorsCloseFAA safety alert that shares operational safety information. 09013, 10017, 15010

Key Concepts

Aviation VHF spectrum: CTAF, UNICOM/MULTICOM, and ground control

• CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. basics. At nontowered airports, pilots use a Common Traffic Advisory Frequency (CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports.) to make position and intention broadcasts. CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. may be a UNICOMUniversal CommunicationsCloseA non-government communication station at some airports for local advisory information., MULTICOMMulticomCloseA self-announce radio frequency used at some airports without another published frequency., Flight Service Station (FSSFlight Service StationCloseFAA-certified briefing support for weather, NOTAMs, and flight information.), or even a tower frequency designated for advisory use, and it is identified in aeronautical publications. UNICOMUniversal CommunicationsCloseA non-government communication station at some airports for local advisory information. is a nongovernment air/ground station that, on request, may provide weather, wind, and recommended runway information. Your exam takeaway: know what CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. means, how it is selected, and that UNICOM/MULTICOM/FSSUNICOM / MULTICOM / Flight Service StationClosePossible providers or frequencies used for local advisory communication at airports without an operating tower. can serve as CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. at airports without an operating control tower. ^[2]

• Ground control segment. The majority of ground control (GCGround ControlCloseTower position or frequency used for surface movement at towered airports.) frequencies occupy the 121.6–121.9 MHz bandwidth. GCGround ControlCloseTower position or frequency used for surface movement at towered airports. exists to keep the tower’s local control frequency clear for arriving and departing aircraft and is limited to communications between the tower and aircraft on the ground, and between the tower and utility vehicles on the airport. For test purposes, recognize both the specific frequency band and the operational limitation: GCGround ControlCloseTower position or frequency used for surface movement at towered airports. is for surface operations only. ^[1]

Frequency-use limitations and best practices around airports

• CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. reporting discipline. Inbound aircraft are expected to report approximately 10 miles from the airport with altitude, aircraft type/ID, relative position, and intent (landing/overflight), and to request wind and runway in use if needed. Additional recommended calls include reports on downwind, base, final, and after leaving the runway. This disciplined, standardized use of the CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. helps deconflict traffic and reduces stepped-on transmissions. ^[3]

• IFRInstrument Flight RulesCloseRules for operating primarily by instruments. On the exam, IFR often appears in weather, traffic, and airspace context. and CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. transitions. When operating on an IFRInstrument Flight RulesCloseRules for operating primarily by instruments. On the exam, IFR often appears in weather, traffic, and airspace context. clearance and ATCAir Traffic ControlCloseThe system that manages controlled airspace, traffic flow, and aircraft separation services. approves a change to the advisory frequency, make an expeditious change to the CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. and use the recommended traffic advisory procedures. This keeps the advisory frequency timely and relevant for all users. ^[3]

• Ground vehicles and CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports.. Airport ground vehicles equipped with radios should monitor the CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. when operating on movement areas and limit transmissions to safety-related matters. This preserves frequency capacity for critical traffic advisories. ^[3]

• Pilot-controlled lighting. Whenever possible, the CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. is used to control airport lighting systems at airports without operating control towers. Be prepared for lighting-control clicks to share the same advisory frequency. ^[3]

Emergency and abnormal situations affecting radio use

• Radio-silent hazards (fueling/HRRHelicopter Rotorcraft RefuelingCloseA specialized refueling procedure referenced in FAA safety examples about radio silence and thunderstorm risk.). During helicopter hover refueling (HRRHelicopter Rotorcraft RefuelingCloseA specialized refueling procedure referenced in FAA safety examples about radio silence and thunderstorm risk.) and similar high-risk refueling operations, radios and certain avionics should be placed in standby-off to prevent electrical discharge or ignition hazards. Do not key the mic or transmit; remember that radio-frequency emissions also come from weather radar, transponders, radar altimeters, DMEDistance Measuring EquipmentCloseRadio navigation equipment that measures distance from a ground station., and ELTs. HRRHelicopter Rotorcraft RefuelingCloseA specialized refueling procedure referenced in FAA safety examples about radio silence and thunderstorm risk. should not be conducted if thunderstorms are within 10 nautical miles, since lightning can travel great distances beyond the storm. These procedures highlight when radio transmissions are operationally limited for safety. ^[7]

• Light gun signals as a no-radio fallback. If transmissions are not possible (lost comms or radio-silent operations), understand the tower light gun meanings:

  • Steady green: Cleared for takeoff (on the ground); Cleared to land (in flight).
  • Flashing green: Cleared for taxi (on the ground); Return for landing (to be followed by steady green) (in flight).
  • Steady red: STOP (on the ground); Give way and continue circling (in flight).
  • Flashing red: Taxi clear of the runway (on the ground); Airport unsafe, do not land (in flight).
  • Flashing white: Return to starting point (on the ground); Not applicable (in flight).
  • Alternating red and green: Exercise extreme caution (both). ^[1]

• Keep advisory frequencies clear for precision operations. Some crewed aircraft may be conducting advanced instrument operations while using or transitioning to the advisory frequency. For example, Enhanced Flight Vision System (EFVSEnhanced Flight Vision SystemCloseA crewed-aircraft system that helps pilots see in low visibility under strict authorization rules.) operations to 100 feet above the touchdown zone elevation are regulated under 14 CFRCode of Federal RegulationsCloseThe federal rulebook where Part 107, Part 89, Part 48, and other aviation rules live. § 91.176(b) and require specific authorization. While not a UASUnmanned Aircraft SystemCloseAn unmanned aircraft plus its control station, communication links, and supporting components. task, this underscores why prompt, concise CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. use and avoiding unnecessary transmissions are essential. ^[6]

Exam focus: Be able to identify where GCGround ControlCloseTower position or frequency used for surface movement at towered airports. frequencies sit in the spectrum (121.6–121.9 MHz) and what they are limited to; define CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. and its possible providers (UNICOM/MULTICOM/FSSUNICOM / MULTICOM / Flight Service StationClosePossible providers or frequencies used for local advisory communication at airports without an operating tower./tower); recall standard CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. reporting points (including approximately 10 miles inbound and “clear of the runway”); know that CTAFCommon Traffic Advisory FrequencyCloseThe frequency pilots use to self-announce near many non-towered airports. may also control lighting; recognize when radio transmissions must be minimized or ceased for safety (e.g., refueling, thunderstorms within 10 NMNautical MileCloseA distance unit used in aviation. One nautical mile is about 1.15 statute miles.); and interpret light gun signals if radios are unavailable.