Section 121.187 - Airplanes: Reciprocating engine-powered: Landing limitations: Alternate airport(a) No person may list an airport as an alternate airport in a dispatch or flight release unless the airplane (at the weight anticipated at the time of arrival at the airport), based on the assumptions in § 121.185 , can be brought to a full stop landing, within 70 percent of the effective length of the runway.(b) This section does not apply to large nontransport category airplanes operated under § 121.173(c) .Doc. No. 6258, 29 FR 19198, Dec. 31, 1964; 30 FR 130, Jan. 7, 1965, as amended by Amdt. 121-251, 60 FR 65928, Dec. 20, 1995