Sec.  22.879   Interference resolution procedures.

   This section applies only to commercial aviation ground stations
   transmitting in the 849–851 MHz band, other than commercial aviation ground
   stations operating under the authority of a license originally granted prior
   to January 1, 2004.

   (a) Initial notification. Commercial aviation air-ground system licensees
   may receive initial notification of interference from non-cellular part 90
   licensees in the 800 MHz band pursuant to  Sec. 90.674(a) of this chapter.

   (1) Commercial aviation air-ground system licensees shall join with part 90
   ESMR licensees and Cellular Radiotelephone Service licensees in utilizing an
   electronic means of receiving the initial notification described in
    Sec. 90.674(a) of this chapter. See  Sec. 22.972.

   (2) Commercial aviation air-ground system licensees must respond to the
   initial notification described in  Sec. 90.674(a) of this chapter as soon as
   possible and no later than 24 hours after receipt of notification from a
   part 90 public safety/CII licensee. This response time may be extended to 48
   hours after receipt from other part 90 non-cellular licensees provided
   affected communications on these systems are not safety related.

   (b) Interference analysis. Commercial aviation air-ground system
   licensees—who receive an initial notification described in  Sec. 90.674(a) of
   this chapter—shall perform a timely analysis of the interference to identify
   the possible source. Immediate on-site visits may be conducted when
   necessary to complete timely analysis. Interference analysis must be
   completed and corrective action initiated within 48 hours of the initial
   complaint from a part 90 public safety/CII licensee. This response time may
   be extended to 96 hours after the initial complaint from other part 90
   non-cellular licensees provided affected communications on these systems are
   not safety related. Corrective action may be delayed if the affected
   licensee agrees in writing (which may be, but is not required to be,
   recorded via e-mail or other electronic means) to a longer period.

   (c) Mitigation steps. Any commercial aviation air-ground system that is
   responsible for causing unacceptable interference to non-cellular part 90
   licensees in the 800 MHz band shall take affirmative measures to resolve
   such interference.

   (1) Commercial aviation air-ground system licensees found to contribute to
   unacceptable interference, as defined in  Sec. 22.877, shall resolve such
   interference in the shortest time practicable. Commercial aviation
   air-ground system licensees must provide all necessary test apparatus and
   technical personnel skilled in the operation of such equipment as may be
   necessary to determine the most appropriate means of timely eliminating the
   interference. However, the means whereby interference is abated or the
   technical parameters that may need to be adjusted is left to the discretion
   of the commercial aviation air-ground system licensee, whose affirmative
   measures may include, but not be limited to, the following techniques:

   (i) Increasing the desired power of the public safety/CII signal;

   (ii) Decreasing the power of the commercial aviation air-ground system
   signal;

   (iii) Modifying the commercial aviation air-ground system antenna height;

   (iv) Modifying the commercial aviation air-ground system antenna
   characteristics;

   (v) Incorporating filters into the commercial aviation air-ground system
   transmission equipment;

   (vi) Changing commercial aviation air-ground system frequencies; and

   (vii) Supplying interference-resistant receivers to the affected public
   safety/CII licensee(s). If this technique is used, in all circumstances,
   commercial aviation air-ground system licensees shall be responsible for all
   costs thereof.

   (2) Whenever short-term interference abatement measures prove inadequate,
   the affected part 90 non-cellular licensee shall, consistent with but not
   compromising safety, make all necessary concessions to accepting
   interference until a longer-term remedy can be implemented.

   (3) When a part 90 public safety licensee determines that a continuing
   presence of interference constitutes a clear and imminent danger to life or
   property, the licensee causing the interference must discontinue the
   associated operation immediately, until a remedy can be identified and
   applied. The determination that a continuing presence exists that
   constitutes a clear and imminent danger to life or property, must be made by
   written statement that:

   (i) Is in the form of a declaration, notarized affidavit, or statement under
   penalty or perjury, from an officer or executive of the affected public
   safety licensee;

   (ii) Thoroughly describes the basis of the claim of clear and imminent
   danger;

   (iii) Was formulated on the basis of either personal knowledge or belief
   after due diligence;

   (iv) Is not proffered by a contractor or other third party; and,

   (v) Has been approved by the Chief of the Wireless Telecommunication Bureau
   or other designated Commission official. Prior to the authorized official
   making a determination that a clear and imminent danger exists, the
   associated written statement must be served by hand-delivery or receipted
   fax on the applicable offending licensee, with a copy transmitted by the
   fastest available means to the Washington, DC office of the Commission's
   Wireless Telecommunications Bureau.

   [ 70 FR 19311 , Apr. 13, 2005]