At the stroke of midnight on New Year's Eve, as you ring out the old year, will you also be ringing out your old 360-channel com radios? If your airplane is so equipped, should you be starting a Christmas wish list of avionics for Santa?
The answer to these questions depends on how you use these radios. They may still be useful in some situations, albeit with some loss of utility.
Beginning January 1, pilots cannot legally transmit over radios with a frequency stability tolerance of more than 0.003 percent (30 parts per million). Most 90- and 360-channel coms and navcoms are at least 20 years old and were built to a frequency stability standard of 0.005 percent (50 parts per million). A few 360- channel radios can be upgraded to meet the new frequency tolerance specifications — expect to pay at least $400 — and the additional channel capability can be added to others (figure on $1,500 or so; a new 760-channel com runs about $3,600 installed). Most of today's aircraft have at least one of the newer 720- or 760-channel radios, which already adhere to the tighter specification.
Benefits accruing to aircraft owners who replace 360-channel coms with their 760-channel brethren include access to more unicom, automated weather observing system/automated surface observing system, automated terminal information service, and air traffic control frequencies, explained Douglas S. Helton, AOPA's vice president for regulatory policy. Additional ATC sectors should reduce congestion on each frequency and may improve the chances for VFR flight following and pop-up IFR clearances. The downside is, of course, the cost of new or upgraded radio equipment.
The stability tolerance change was mandated by the Federal Communications Commission in 1984, following the adoption of an international agreement at the World Administrative Radio Conference in 1979. The tighter frequency stability specification is intended to prevent interference with transmissions on adjoining frequencies and allows the change from 50-kHz frequency spacing to 25-kHz spacing, essentially doubling the number of available aeronautical frequencies.
These radios have been threatened with obsolescence since the early 1980s, but determined action by AOPA through the years delayed the deadline until now. Interestingly, there is no FAA requirement for use of the newer 720- or 760-channel coms — although any pilot using 360-channel coms and flying much en route IFR during the past few years certainly has been inconvenienced by an inability to accept assigned frequencies.
According to the 1996 AOPA Fact Card, during 1994 — the last year for which complete data were available — there were 59,369 360-channel radios in the U.S. general aviation fleet. Many of these radios meet the 0.003 percent requirement; some as built, and others through the use of modification kits available from the manufacturer. A sizable number of these remaining 360-channel radios are used as secondary coms, Helton explained.
An informal survey of members telephoning AOPA's toll-free information lines in July indicated that 29 percent of survey respondents normally fly a general aviation aircraft equipped with a 360-channel radio. But 63 percent of those aircraft- -more than three out of five — also are equipped with a 720-channel radio. Sixty-nine percent of members responding said they were aware of the FCC requirement's taking effect at the end of the year. Results of the informal survey probably are overstated because the sample wasn't limited to aircraft owners, Helton said.
The issue has also received attention in the AOPA Online forum on CompuServe. "I know people at my own airport, just outside the (Chicago) O'Hare Mode C veil, who are fighting to keep these old radios alive until they have to change them," read an Illinois member's forum posting. "One guy has spent $500 on maintenance in the last year, with five trips to the radio shop, because he's not going to replace the radio until January 1."
AOPA has fought the changes since they were proposed, Helton said. "We've opposed this all along, and delayed it as long as we could. But we've reached the point that owning 760-channel radios provides real benefits to general aviation, and owners of noncompliant 360-channel radios have received a good return on their investment. Those pilots who fly VFR only and rarely need to transmit can continue to use these radios to monitor broadcast advisories, and use low-cost handhelds on those few occasions when they need to transmit."
Despite many years' notice, implementation of this FCC requirement apparently is surprising some pilots. The December 1980 AOPA Newsletter, an association publication that has metamorphosed into what is now "AOPA Action" in the pages of AOPA Pilot, admonished that "you'll soon need avionics systems with 720 com channels (25-kHz frequency separation) if you want to enjoy unrestricted access to the ATC system." (The same newsletter announced that Chicago Mayor Jayne Byrne remained committed to closing Meigs Field and turning the airport property into — you guessed it — a park.) Several extensions of the implementation deadline for the new radio frequency tolerance requirements have been reported in AOPA Pilot.
History
The steady growth of aviation has brought about corresponding increases in air/ground communications requirements, according to FAA Advisory Circular AC 90- 50D, Requirements for 760-Channel VHF Radios for Aeronautical Operations. Further, the growing diversity of air traffic has resulted in an increasingly complex air traffic control environment, which adds to the demand for spectrum efficiency. The radio spectrum from 118.000 to 135.975 MHz is used for air/ground communications in the aeronautical mobile service. Reducing the bandwidth requirements to 25 kHz doubles the available assignment pool to 720 channels. Retaining 100 kHz protection for the 121.5 MHz emergency channel reduces the 720 channels to 714.
In 1973 an FAA Notice of Policy Decision informed the public that the FAA was planning to increase the air traffic control communications capability by dividing the available spectrum into 25 kHz assignments. This implementation of 25 kHz frequencies for high-altitude en route air traffic control sectors began in 1977.
Another FAA Notice of Policy Decision in 1984 announced that the FAA would continue to increase ATC communication capability by expanding the use of 25 kHz assignments in the low-altitude sectors. AOPA efforts helped to delay implementation of these frequencies at lower altitudes.
Following the 1983 U.S. ratification of the provisions of the 1979 World Administrative Radio Conference (WARC '79), the Federal Communications Commission issued, in 1984, an amendment to the FCC Rules and Regulations concerning frequency stability tolerances for aviation services. The frequency stability tolerances for the aeronautical mobile band were reduced from 0.005 percent to 0.003 percent for all new and replacement radios installed after January 3, 1985, and for all radios after January 1, 1990. After AOPA petitioned for reconsideration, the implementation was delayed until 1992. Then, in 1991, FCC determined that January 1, 1997, was the latest that it could allow "grandfathering" of all VHF aircraft station radios certified to the old frequency tolerance standards.
Another WARC '79 provision was the reallocation of the 136.000 to 136.975 MHz band to aeronautical use. Radios capable of operation in the 118.000 through 136.975 MHz range offer 760 channels and ensure full air traffic control communications. Unrestricted instrument flight rules operation requires 25-kHz radios.
Upgrading airborne equipment to 720/760-channel radios will provide access to three additional unicom channels in the 118 to 136 MHz band (122.275, 122.975, 123.075), and 760-channel radios could provide access to as many as five unicom channels in the 136 to 136.975 MHz band. New automated weather observation facilities are likely to receive frequency assignments in this band as well.
What to do?
Because this is an FCC radio rule, the FAA is not responsible for enforcing the measure — although it could report instances of noncompliance to FCC. "The FAA has told us that it doesn't plan on initiating any special enforcement — or surveillance, if you will — efforts," said AOPA's Helton.
According to Helton, FCC plans to issue a policy statement in the coming months which will state that noncomplying radios can remain in the airplane, as long as they are not used for transmission. "We want to dispel the notion that all these radios must be removed from the aircraft by the end of this year," he said. "Another myth is that if an airplane with one of these radios goes into repair for something unrelated to the radio, an A&P cannot legally return the aircraft to service until the radio is removed. This is simply not true."
Helton's opinion is that owners do not need to replace these radios unless they become unservicable, although pilots should not use them after January 1 to transmit except in an emergency. He suggests that flying clubs and pilots who might let others fly their airplanes placard "Receive only" any old radios not meeting the new FCC standards.
Unresolved is the question of whether these old radios may be repaired and returned to service. At press time, AOPA was negotiating with FCC to permit the radios to be returned to service with an appropriate placard. (Any developments will be reported in "AOPA Action" in future issues of Pilot.)
The future
While many pilots in the United States face the prospect of upgrading 360-channel com radios, they may not be alone. The International Civil Aviation Organization has called for further splitting of European VHF voice channels from 25-kHz frequency spacing to 8.33 kHz (see " Pilot Briefing," page 40). According to traffic estimates, some areas could run out of frequencies as soon as 1998.
While that move may force European pilots to upgrade considerably newer radios, such a change isn't likely here anytime soon. "The FAA believes that the United States won't encounter similar problems until at least 2003 and that the 8.33 split will only delay the day of reckoning for 10 to 15 years," Helton said. "Instead, the FAA plans on transitioning to digital radio over about a 20-year period." Digital coms will quadruple the number of frequencies, he added, but timing, funding, and user support for a move to either technology here are still in question.
Out of Spec
Radios that don't meet new tolerance requirements
The following panel-mount radios, 360-channel (or fewer) transceivers, do not meet the 0.003-percent frequency tolerance that will be required by the FCC, starting on January 1, 1997. A few of these radios can be modified to meet the new standards, and some of those can be further modified with 760-channel capability. Any radios not listed should meet the new requirements. AOPA is not aware of any handheld radios that do not meet the new FCC specifications.
AlliedSignal Commercial Avionics System (formerly Bendix/King), 400 N. Rogers Road, Olathe, Kansas 66062; 913/782-0400. Models: KX 100, KX 100A, KX 110, KX 120, KX 130, KX 150, KX 150A, KX 150B, KX 160, KX 160-1, KY 90, KY 90A, KY 95, RT-221, RT-221A-14, RT-221A-28, RT-221AE-14, RT-221AE-28, RT-241A, 350A1, 350B1, 351A, 351AE, 351B, 351BE, TA18BB-1, TA18C-1, TA20-A-1A, TA20-B-1A, TA21-A- 1, TA22A, and TA22B. (Note: King's KX 170, KX 170A, KX 175, KX 175A, and KY 195 can be upgraded to meet the new frequency tolerance, but they will remain 360-channel radios. Cost of the upgrade is $322 for parts plus 3 to 4 hours of labor).
Rockwell (Collins Division), 400 Collins Road N.E., Building 105, Cedar Rapids, Iowa 52498; 319/295-1000. Models: 17L3, 17L4, 17L6, 17L7, 17L7A, 17L8A, 17M1, 618F-1, 618F-1A, 618F-1B, 618F-1C, 618F-1D, 618M-1, 618M-1A, 618M-1B, 618M- 1C, and 618M-1D.
Aire-Sciences (Edo Aire), 19A Gardner Road, Fairfield, New Jersey 07004; 201/575-7725. Models: RT 551, RT 553, RT661, RTD 771, RT 771, RT 771A, and RT 773.
Genave, 1120 220th Street West, Farmington, Minnesota 55024; 612/460-6616. Models: Alpha 300 and Alpha 360.
Narco Avionics, 270 Commerce Drive, Fort Washington, Pennsylvania 19034; 800/223-3636. Models: MK 3, MK 4, MK 6, MK 7, MK 8, MK 12, MK 12A, MK 12B, MK 16, MK 24, Escort 110, Com 16, Com 100, and VGTR 3A. (Com-10/10A and Com-11/11A may require alignment or crystal replacement.)
Sigma Tek (formerly Cessna), 1001 Industrial Road, Augusta, Kansas 67010; 316/775-6373. Models: CC301A, CC3013A, CC304A, CC312A, CC313A, CC313E, CC315A, CC401A, CC402A; (formerly ARC) 7005UAMNW-D, 7005UAXNW-D, 7025UAMVW-T, 7025UAXVW-T, 7027UAMNW-F, 7027UAMNW-FL, 7027UAXNW-F, 7027UAXNW-FL, T-22, T-25A, T25B, T-25C, T-25D, T-27A, RT-11A, RT-11B, RT- 11C, RT-11D, RT-131A, RT-302A, RT-302G, RT-317A, RT-317G, RT-317G-1, RT-321A, RT- 328A, RT-331A, RT-422A, RT-432A, RT-503A, RT-508A, RT-513A, RT-513A-20, RT- 515A, RT-515R, RT-515R-1, RT516R, RT-517R, RT-522A, RT-524A, RT-528A, RT- 528E, RT-532A, and RT-540A.
Sunair Electronics, 3101 S.W. Third Avenue, Fort Lauderdale, Florida 33315; 954/525-1505. Models: SA 1036, SA 360, SA 360E, and SA 90.
Trimble Navigations (formerly Terra, also includes Bertea/General Avionics prior to 1972 and Radair/Dynair prior to 1978), 2105 Donley, Austin, Texas 78758; 888/FLY-TRMB. Models: ML 200, ML 360, R 360, and R 10.
Conversions or replacements are available for some 360-channel radios.
Narco Avionics (telephone number above) offers slide-in replacement radios, which utilize the exisiting mounting tray and wiring harness, for several series of Narco and Cessna radios.
McCoy Avionics Corporation offers frequency stabilization and 760-channel conversion kits for King KX 170- and 175-series radios. Write to 10761 Watkins Road, Marysville, Ohio 43040-9544; telephone 800/654-0220 or 513/642-8080; fax 513/642-0220.
TKM Inc. offers slide-in replacements for a variety of Cessna, King, and Narco radios. For more information, contact a TKM dealer: Edmo Distributors, 800/235- 3300; Hawkins Associates, 800/433-2612; or U.S. Avionics, 800/444-1115. For additional information, contact the FCC Wireless Telecommunications Bureau at (202) 418-0680 or e-mail [email protected].
