All:
I'd like to know what "frequency protection" means, in an IFR context. I'll deliver a great example of California brewing to a San Diego airport (OKB, RNM, MYF...) for the first who can provide a useful definition, with a reference.
From my research, my theory is that the term means the FAA has, in coordination with other spectrum users:
a) placed the navaid at such a distance that signal is not lost between stations along the same route,
AND
b) set the power of the navaid FAA nav/com signal such that it does not interfere with other coordinates uses of the same frequency,
AND
b) confirmed the frequency is protected, by distance, spectrum separation, or other means, from interference with other legitimate users of the same frequency ?
I first saw the terms in a Navigation and Communication box on the L-3/L-4 IFR low chart:
"(T) Frequency Protection - usable range 25NM at 12500 AGL" at the Camp Pendleton TACAN;
the FAA Aeronautical Chart User?s Guide, 12th Edition, October, 2013, has the same descriptive text under the "IFR Terms" tab, but no definition of the terms.
I haven't found a definition in my usual IFR sources:
Airplane Flying Handbook
Instrument Procedures Handbook
Instrument Flying Handbook
The first CFI I asked didn't know; I'm trying others as well.
Some references speak to the concept, but I haven't found a definitive, um... definition.
FAA Great Lakes Region Order, GL 6050.l2A, 11/25/77 "EXPANDED SERVICE VOLUMES FOR NAVAIDS (ESV) "
Section 4 states:
" BACKGROUND. The usable distance and altitude of NAVAIDs is determined by protection from radio frequency interference. Geographical separation of NAVAID utilized to establish frequency protection. The responsibility for providing this protection and assignment of frequencies will be provided by the Regional Frequency Engineering Office, AGL-438. NAVAIDs are frequency protected and flight checked to the normal NAVAID use limitations listed in Handbook 7110.65. "
FAA Order 6510.4A, 6/19/80, " RADIO COMMUNICATIONS REQUIREMENTS FOR AIR TRAFFIC CONTROL FACILITIES " section 4.d states:
"GENERAL.
a. Frequency protection shall be provided air/ground communications frequency assignments (except tor BUEC) which are engineered to meet the operational requirements of air traffic control facilities'.- This [demands the provision of frequency protection for co-channel and adjacent channel separation within prescribed distances, depending on the type of air traffic service involved. "
section 4.i states:
"Service Volume - The vertical and horizontal limits of airspace within which an assigned frequency is used. These limits are used to determine frequency protection Iron other frequency assignments. The service volume should represent the desired coverage area to ensure safe usage. "
FAA Order JO 7400.2H, March 10, 2011, " Procedures for Handling Airspace Matters" Section 20-4-2 states:
"NAVAID SPACING
Jet routes are normally based on ?H" class NAVAIDs spaced no farther apart than 260 NM or non-VOR/DME area navigation system performance. They may be based on more widely spaced NAVAIDs if a usable signal can be provided (e.g., GPS) and frequency protection afforded for the distance required."
FAA Order 7400.2F, 02/16/06 "PROCEDURES FOR HANDLING AIRSPACE MATTERS" section 20-3-1 states:
"NAVAID SPACING
a. VOR Federal airways are based on NAVAIDs which normally are spaced no farther apart than 80 NM. They may be based on more widely spaced NAVAIDs if a usable signal can be provided and frequency protection afforded for the distance required (see Order 9840.1, U.S. National Aviation Handbook for the VOR/DME/TACAN Systems).
b. NAVAID spacing for L/MF airways has no standard but is determined on an individual basis. "
I'd like to know what "frequency protection" means, in an IFR context. I'll deliver a great example of California brewing to a San Diego airport (OKB, RNM, MYF...) for the first who can provide a useful definition, with a reference.
From my research, my theory is that the term means the FAA has, in coordination with other spectrum users:
a) placed the navaid at such a distance that signal is not lost between stations along the same route,
AND
b) set the power of the navaid FAA nav/com signal such that it does not interfere with other coordinates uses of the same frequency,
AND
b) confirmed the frequency is protected, by distance, spectrum separation, or other means, from interference with other legitimate users of the same frequency ?
I first saw the terms in a Navigation and Communication box on the L-3/L-4 IFR low chart:
"(T) Frequency Protection - usable range 25NM at 12500 AGL" at the Camp Pendleton TACAN;
the FAA Aeronautical Chart User?s Guide, 12th Edition, October, 2013, has the same descriptive text under the "IFR Terms" tab, but no definition of the terms.
I haven't found a definition in my usual IFR sources:
Airplane Flying Handbook
Instrument Procedures Handbook
Instrument Flying Handbook
The first CFI I asked didn't know; I'm trying others as well.
Some references speak to the concept, but I haven't found a definitive, um... definition.
FAA Great Lakes Region Order, GL 6050.l2A, 11/25/77 "EXPANDED SERVICE VOLUMES FOR NAVAIDS (ESV) "
Section 4 states:
" BACKGROUND. The usable distance and altitude of NAVAIDs is determined by protection from radio frequency interference. Geographical separation of NAVAID utilized to establish frequency protection. The responsibility for providing this protection and assignment of frequencies will be provided by the Regional Frequency Engineering Office, AGL-438. NAVAIDs are frequency protected and flight checked to the normal NAVAID use limitations listed in Handbook 7110.65. "
FAA Order 6510.4A, 6/19/80, " RADIO COMMUNICATIONS REQUIREMENTS FOR AIR TRAFFIC CONTROL FACILITIES " section 4.d states:
"GENERAL.
a. Frequency protection shall be provided air/ground communications frequency assignments (except tor BUEC) which are engineered to meet the operational requirements of air traffic control facilities'.- This [demands the provision of frequency protection for co-channel and adjacent channel separation within prescribed distances, depending on the type of air traffic service involved. "
section 4.i states:
"Service Volume - The vertical and horizontal limits of airspace within which an assigned frequency is used. These limits are used to determine frequency protection Iron other frequency assignments. The service volume should represent the desired coverage area to ensure safe usage. "
FAA Order JO 7400.2H, March 10, 2011, " Procedures for Handling Airspace Matters" Section 20-4-2 states:
"NAVAID SPACING
Jet routes are normally based on ?H" class NAVAIDs spaced no farther apart than 260 NM or non-VOR/DME area navigation system performance. They may be based on more widely spaced NAVAIDs if a usable signal can be provided (e.g., GPS) and frequency protection afforded for the distance required."
FAA Order 7400.2F, 02/16/06 "PROCEDURES FOR HANDLING AIRSPACE MATTERS" section 20-3-1 states:
"NAVAID SPACING
a. VOR Federal airways are based on NAVAIDs which normally are spaced no farther apart than 80 NM. They may be based on more widely spaced NAVAIDs if a usable signal can be provided and frequency protection afforded for the distance required (see Order 9840.1, U.S. National Aviation Handbook for the VOR/DME/TACAN Systems).
b. NAVAID spacing for L/MF airways has no standard but is determined on an individual basis. "