There are odd 20kHz channel spacings between channels 3/4, 7/8, 11/12, 15/16 and 19/20. These 'unused' frequencies are used by remote controlled toys such as toy boats and toy cars. These frequencies cannot be used by remote controlled aircraft, due to interference by CB radio in close proximity, which could crash the plane or helicopter into the ground, an object, or even a person. For this reason model aircraft use only the 72.0~73.0MHz band instead, which contains 50 channels.
This assignment of channels to frequencies has been adopted by many countries worldwide, including the U.K, although some countries have only approved the use of the first 22 channels.
The channel/frequency allocation for the 40 channels are as follows:
Channel Frequency Channel 01 26.965 MHz Channel 02 26.975 MHz Channel 03 26.985 MHz Channel 04 27.005 MHz Channel 05 27.015 MHz Channel 06 27.025 MHz Channel 07 27.035 MHz Channel 08 27.055 MHz Channel 09 27.065 MHz (emergency channel) Channel 10 27.075 MHz Channel 11 27.085 MHz Channel 12 27.105 MHz Channel 13 27.115 MHz Channel 14 27.125 MHz Channel 15 27.135 MHz Channel 16 27.155 MHz Channel 17 27.165 MHz Channel 18 27.175 MHz Channel 19 27.185 MHz Channel 20 27.205 MHz Channel 21 27.215 MHz Channel 22 27.225 MHz Channel 23 27.255 MHz Channel 24 27.235 MHz Channel 25 27.245 MHz Channel 26 27.265 MHz Channel 27 27.275 MHz Channel 28 27.285 MHz Channel 29 27.295 MHz Channel 30 27.305 MHz Channel 31 27.315 MHz Channel 32 27.325 MHz Channel 33 27.335 MHz Channel 34 27.345 MHz Channel 35 27.355 MHz Channel 36 27.365 MHz Channel 37 27.375 MHz Channel 38 27.385 MHz Channel 39 27.395 MHz Channel 40 27.405 MHzThe frequency allocation list is supplied by the FCC (Federal Communications Commission) from Part 95 - Subpart D - Rules for CB Service Citizens Band (CB) Radio Service.
See also: GMRS, FRS, MURS