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Commonly Asked Aeronautical Frequency Notification (AFN) Questions

Q:  What are Aeronautical Frequency Notifications?
A:  Cable operators planning to use the frequencies in the aeronautical communications or navigational frequency bands must notify the Commission prior to the activation of these frequencies.  This is done via the Cable Operations and Licensing System (COALS) on the FCC's website.  The requirement is in Sec. 76.1804 of the rules.  47 C.F.R. §76.1804.  Additional requirements for using the aeronautical bands are contained in Sections 76.605, 76.610, 76.611, 76.613, 76.614, and 76.616.

Q:  When should the cable company file Aeronautical Frequency Notifications with the Commission?
A:  The Aeronautical Frequency Notifications must be filed prior to operating in the aeronautical bands.

Q:  How often should the cable company file Aeronautical Frequency Notifications?
A:  The Aeronautical Frequency Notifications should be filed initially when the cable system starts operating in the Aeronautical Frequency band, or when modifications to the system are being made. Refer to Sec. 76.1804 of the rules.  47 C.F.R. §76.1804.

Q:  What form should the cable operator use to file to the Aeronautical Frequency Notifications?
A:  You must file the Aeronautical Frequency Notification electronically using

Q:  If my headend serves multiple community units (CUIDs), how should I file Aeronautical Frequency Notifications?
A:  File a single Aeronautical Frequency Notification for all communities served from a single headend.

Q:  How do I convert from miles to kilometers?
A:  The formula is:  1 mile = 1.609344 kilometers

Q:  I transmit digital and analog, what should I enter in modulation?
A:  Enter the type of modulation you are transmitting on each channel, digital, AM or FM.

Q:  What are frequency offsets?
A:  The video carrier of analog cable channels must be separated in frequency from the assigned carriers of aeronautical stations.  This table provides the aeronautical frequency offsets

Frequency Band (Standard and IRC)OffsetTolerance
118-137, 225-328.6 and 335.4-400 MHz12.5 kHz+ - 5 kHz
108-118 and 328.6-335.4 MHz25.0 kHz+ - 5 kHz

For Harmonically Related Carrier (HRC) systems, the fundamental frequency from which the visual carrier frequencies are derived should be a multiple of 6.0003 MHz with a tolerance of + - 1 Hz.



  • Harmful interference is any emission, radiation or induction that endangers the functioning of a radio-navigation service or of other safety services or seriously degrades, obstructs or repeatedly interrupts a radio communication service.
  • The operator of a cable television system that causes harmful interference must promptly eliminate the harmful interference.
  • If harmful interference to radio communications involving safety of life cannot be eliminated, operation of the offending cable television system or appropriate elements of it must be suspended immediately upon notification by the District Director of the Commission's local field office and must not be resumed until the interference has been eliminated to the satisfaction of the District Director.  When authorized by the District Director, short test operations may be made during the period of suspended operation to check whether the interference has been eliminated.
  • The cable television system operator may be required by the District Director to submit a report on the cause(s) of the interference, corrective measures taken, and the progress in correcting the interference.

FCC Media Bureau > Engineering Division


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