Communications Altitude & Geographic Restrictions

In accordance with CAPR 100-1, Radiotelephone Operations, CAP National Headquarters may issue guidance on altitude restrictions for CAP’s VHF-FM frequencies. These restrictions must align with international agreements and regulations from frequency management agencies.

CAP works with the Air Force's Spectrum Management Office (AFSMO) to document CAP’s VHF-FM assignments and altitude authorizations. However, some legacy users of CAP’s frequencies remain active, and CAP must be mindful of potential interference, especially during aircraft operations.

Current Altitude Restrictions

• Canadian and Mexican Border Zones:

  • Canada: CAP’s assigned VHF-FM frequencies may not be used above 3,000 feet AGL within the Canadian Border Zone, as outlined in international agreements.

  • Mexico: CAP may not operate above 3,000 feet AGL within the Mexican Border Zone, which extends approximately 140 km (90.1 statute miles) from the U.S.-Mexico border.

• Other Areas:

  • Outside of the border zones, CAP may operate on assigned VHF-FM frequencies at any altitude up to 12,500 feet AGL, pending safe and effective mission execution. These guidelines are based on informal guidance from AETC and AFFMA until further notice.

Border Zone Definitions

• Canadian Border Zone:

  • The Canadian Border Zone for the continental U.S. is defined by international treaty as Line A, and for Alaska, it is referred to as Line C.

  • Detailed maps of Line A for each affected CAP Wing are available in the provided PowerPoint slides and a downloadable Communications Border Zone Maps Zip File.

• Mexican Border Zone:

  • The Mexican Border Zone is approximately 140 km (90.1 statute miles) from the U.S.-Mexico border, as depicted in the map provided.

CAP Radio Frequency Restrictions – Canadian Border Zone

In accordance with CAPR 100-1, CAP National Headquarters issues guidance on communications restrictions within geographically defined areas due to international agreements. CAP members operating near the Canadian border must follow these restrictions carefully.

Simplex Communications Restrictions

• Authorized Channels: Within the Border Zone, only Air 1 and CAPGUARD are authorized for use at full power, with the exception of the 3,000-foot AGL limitation.

• Limited Power: All other CAP Simplex channels, except TAC 1, may be used within the Border Zone but are limited to 5 watts output power or less. Airborne use of these channels should be minimized to avoid interference with Canadian operations.

• TAC 1: This channel is used as a CAP repeater input and should conform to the Region Repeater Committee recommendations.

Repeater Restrictions

• CAP’s standard repeater input frequencies are not authorized in the Border Zone. Repeaters within or adjacent to the Border Zone use special input frequencies, identified as R101 through R108. These repeaters may be used to communicate through Border Zone repeaters regardless of the user’s location.

Altitude Restrictions

• Within the Border Zone, CAP aircraft are authorized to transmit below 3,000 feet AGL.

• Outside of the Border Zone, CAP may operate up to 12,500 feet AGL. However, aircraft should limit the use of Simplex channels other than Air 1, TAC 1, and CAPGUARD to avoid interference with Canadian operations.

CAP Radio Frequency Restrictions – Mexican Border Zone

Within the Mexican Border Zone, CAP aircraft must follow these restrictions:

• CAP’s airborne transmitters must not be used above 3,000 feet AGL when operating on CC1, CC2, TAC 1, or any repeater channel.

• Repeater output frequencies are unaffected and may be used in accordance with CAPR 100-1.

Regional Frequency Restrictions

Northeast Region (Maine, New Hampshire, Vermont, New York, Pennsylvania)

• Simplex:

  • Air 1 and CAPGUARD are authorized for unrestricted use within the Border Zone, with the exception of the 3,000-foot AGL limitation.

  • Other CAP Simplex channels (except TAC 1) may be used within the Border Zone at 5 watts output power or less. However, airborne operations on these channels should be minimized to avoid interference with Canadian operations.

  • TAC 1 serves as a CAP repeater input and must adhere to the Region Repeater Committee’s guidelines.

• Repeater:

  • Standard CAP repeater input frequencies are not authorized in the Border Zone. Special repeater input frequencies, designated R101-R108, are used for CAP communications in this region.

  • Tactical repeater channels are also not authorized, except for the special Border Zone tactical channel.

• Altitude Restrictions:

  • CAP aircraft can transmit below 3,000 feet AGL within the Border Zone. Outside the Border Zone, CAP can operate occasionally up to 12,500 feet AGL. However, use of Simplex channels (other than Air 1, TAC 1, and CAPGUARD) should be minimized above 3,000 feet AGL to avoid interference with Canadian operations.

Great Lakes Region (Ohio, Michigan, Wisconsin)

• Simplex:

  • CAPGUARD and TAC 1 may be used without restriction. Channels CC 1, Air 1, and Air 2 can be used within the Border Zone, but avoid operations near the following Canadian locations:

    • CC 1: Avoid within 60 km of:

      • Sault Ste. Marie: 46°30’17”N X 84°19’20”W

      • Leamington: 42°02’26”N X 82°36’02”W

      • Chatam: 42°25’00”N X 82°11’59”W

      • Oxford: 42°48’11”N X 81°57’09”W

    • Air 1: Avoid within 120 km of:

      • Sault Ste. Marie: 46°30’17”N X 84°19’12”W

      • Sarnia: 42°58’25”N X 82°23’20”W

      • Wallaceburg: 42°35’05”N X 82°27’02”W

      • Windsor: 42°18’25”N X 83°01’52”W

    • Air 2: Avoid within 220 km of:

      • Tehkummah: 45°39’10”N X 82°00’57”W

      • Watford: 43°01’43”N X 81°57’09”W

      • Brantford: 43°08’18”N X 80°15’48”W

  • Other CAP Simplex channels are allowed at 5 watts output power or less, but airborne operations should be minimized.

• Repeater:

  • CAP repeater channels in this region have been adjusted, and operations must utilize R64 or authorized Channel 2 repeater frequencies within the Border Zone.

• Altitude Restrictions:

  • Transmissions are restricted below 3,000 feet AGL within the Border Zone. Outside the Border Zone, operations up to 12,500 feet AGL are permitted but should avoid interference above 3,000 feet AGL.

North Central Region (Minnesota, North Dakota)

• Simplex:

  • TAC 1 and Air 1 may be used without restriction. CC 1 and CAPGUARD are allowed with the following distance restrictions:

    • CC 1: Within 120 km of:

      • Minton: 49°06’10”N X 104°44’35”W

    • CAPGUARD: Within 120 km of:

      • Halbrite: 49°30’31”N X 103°35’16”W

  • All other CAP Simplex channels are limited to 5 watts output power within the Border Zone, and airborne use should be minimized.

• Repeater:

  • Channel 2 repeater input frequencies are not authorized within the Border Zone. CAP repeaters in the area operate on Channel 1.

• Altitude Restrictions:

  • CAP aircraft are restricted to below 3,000 feet AGL in the Border Zone. Occasional operations up to 12,500 feet AGL are permitted outside the Border Zone, but caution should be used to avoid interference above 3,000 feet AGL.

Rocky Mountain Region (Montana, Idaho)

• Simplex:

  • TAC 1 and Air 1 are authorized within the Border Zone with the 3,000-foot AGL restriction.

  • CC 1 may be used except within 120 km of:

    • Minton: 49°06’10”N X 104°44’35”W

    • Maple Creek: 49°55’30”N X 109°28’48”W

  • CC 2, Air 2, and CAPGUARD are not authorized within the Border Zone.

• Repeater:

  • Channel 2 repeaters are not authorized within the Border Zone. Use of Channel 1 and Tactical repeaters is permitted.

• Altitude Restrictions:

  • CAP aircraft may transmit below 3,000 feet AGL in the Border Zone. Outside, occasional operations up to 12,500 feet AGL are allowed, with a focus on avoiding interference.

Pacific Region (Washington State)

• Simplex:

  • TAC 1 and Air 1 are authorized within the Border Zone with the 3,000-foot AGL restriction.

  • CC 1 may be used except within 120 km of:

    • Cowichan: 48°49’29”N X 124°03’01”W

  • CC 2, Air 2, and CAPGUARD are not authorized within the Border Zone.

• Repeater:

  • Channel 2 repeaters are not authorized within the Border Zone. Use of Channel 1 and Tactical repeaters is permitted.

• Altitude Restrictions:

  • Transmissions must remain below 3,000 feet AGL within the Border Zone. Outside the zone, operations up to 12,500 feet AGL are permitted, with restrictions to minimize interference.

Pacific Region (Alaska)

• Simplex:

  • CC 1, CC 2, and Air 2 may be used without restriction in the Border Zone.

  • Air 1 is restricted within 50 km of:

    • Nass Valley: 55°14’02”N X 129°02’24”W

  • CAPGUARD is not authorized within the Border Zone.

• Repeater:

  • No repeater restrictions within the Border Zone, but the 3,000-foot AGL altitude limit applies.

• Altitude Restrictions:

  • Within the Border Zone, CAP aircraft are limited to 3,000 feet AGL. Outside the zone, operations up to 12,500 feet AGL are allowed, with awareness of potential interference.