Sec.  87.219   Automatic operations.

   (a) A station operator need not be present when an automated unicom is in
   operation.

   (b) Unicoms operating in an automated mode must comply with the requirements
   of paragraphs (1)–(5) of this section, in addition to the requirements
   applicable to non-automated unicom operations.

   (1) An automated unicom must transmit only in response to interrogating
   signals from aircraft, including but not limited to the brief keyed RF
   signals specified in  Sec. 87.187(y).

   (2)  An  automated  unicom  must monitor the unicom frequency prior to
   transmission, and provide a brief delay between the aircraft's interrogating
   signal and the automatic unicom's response.

   (3) Automated advisory transmissions must be as brief as possible, and must
   never exceed one minute in length.

   (4) An automated unicom may not provide weather information at an airport
   that has an operational, FAA-certified, automatic weather facility, unless
   the unicom itself is certified by the FAA.

   (5) If weather information is provided by an automated unicom:

   (i) weather sensors must be placed in order to adequately represent the
   weather conditions at the airport(s) to be served;

   (ii) the weather information must be proceeded by the word “advisory;”

   (iii) the phrase “automated advisory” must be included when the weather
   information was gathered by real-time sensors or within the last minute;
   and,

   (iv) the time and date of the last update must be included when the weather
   information was not gathered within the last minute.

   (c) Only one automated unicom may be operated at an uncontrolled airport.
   Prior to the operation of an automated unicom at an airport with more than
   one unicom licensee, all of the licensees at that airport must sign a letter
   of  agreement  stating  which licensee(s) control the automated unicom
   operations, and, if control is to be shared among several operators, how
   that control will be divided or scheduled. The original or a copy of the
   letter of agreement must be kept with each licensees' station records.
   Within 90 days of the date upon which a new unicom operator is licensed at
   an airport where more than one unicom is authorized, and an automated unicom
   is being operated, an amended letter of agreement that includes the new
   licensee's signature must be signed or automated unicom operations must
   cease.

   [ 64 FR 27475 , May 20, 1999]

Subpart H—Aeronautical Multicom Stations