. 122.750/122.850 MHz – Air-to-air

. 126.200 MHz – Military airports

. 122.000 MHz – Flight Watch/FSS

. 122.900 MHz – Common Traffic Advisory Frequency (CTAF)

. 123.100 MHz – SAR frequency, air-to-air

 
B.2.  Marine Band/Coast Guard Frequencies
 Auxiliary aircraft carry one or more radio transceivers operating on VHF-FM in the frequency range of 156.050 to 162.025 MHz.  Most VHF-FM marine-band transceivers used in Auxiliary aircraft are not designed to fit in the standard aircraft stack.  These essential radios are usually mounted wherever space permits their safe mounting.  Sometimes, due to switching or wiring complexities, the marine band radio cannot be interconnected with the aircraft microphone system, thus requiring a separate microphone.  A less desirable method to obtain VHF-FM-band communications is to use a portable, handheld unit.  In either case, an attachment to an external antenna is part of the facility requirements.  The following are common frequencies for Coast Guard Auxiliary communications from aircraft:
. Channel 16 (156.800 MHz) – Maritime Distress and Calling

. Channel 21 (157.050 MHz) – CG Working Frequency

. Channel 22 (157.100 MHz) – CG to Public Liaison Frequency

. Channel 23 (157.150 MHz) – CG Working Frequency

. Channel 81 (157.075 MHz) – CG Working Frequency

. Channel 83 (157.175 MHz) – CG Working Frequency

 
B.3.  VHF-FM Transceiver Installation
 The installation should be designed to use the aircraft electrical system for power or battery charging of the marine radio, and should also use the aircraft intercom system to permit all crewmembers to hear the marine transmissions.  The antenna should be hull mounted to the bottom of the aircraft for best results and dedicated exclusively to the VHF-FM radio.  It may be incorporated as part of a “Y” lead for emergency use handheld VHF-AM units.  It is important that all onboard are able to hear the communications on the VHF-FM unit in order to ensure effective CRM principles and reduce time and error in passing along information within the aircraft.  Figure 6-1 illustrates one method of connecting a handheld or portable marine unit to the aircraft systems.
Since common aircraft power systems are either 12- or 24-volt, a power converter may be needed to connect to the transceiver power or charging port.
 
Interconnection of VHF-FM Transceiver in Auxiliary Aircraft
 
 
Figure 6-1 Interconnection of VHF-FM Transceiver in Auxiliary Aircraft
 

 
 
B.4.  VHF-FM Transceiver Usage
 In aircraft use, the microphone may pick up aircraft noise if it is not a noise-canceling type.  This may make aircraft transmissions difficult to understand. For reception, an intercom connection is superior to a single earpiece.  However, if an intercom is not available, an earpiece alone may be required.
　
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