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121.321-1 - Compliance with Requirements of § 121.321, Operations in Icing

Date Issued
August 04, 2011
Responsible Office
ANM-100,  Aircraft Certification Service, Transport Airplane Directorate

This advisory circular (AC) describes an acceptable means for showing compliance with the requirements of Title 14, Code of Federal Regulations (14 CFR) 121.321, Operations in Icing.  Part 121 contains the aircraft operating requirements applicable to domestic, flag, and supplemental operations.  This AC provides guidance for:

a.   Using visible moisture and temperature as a means for the flightcrew to know when the airframe ice protection system (IPS) must be activated.

b.   Developing acceptable procedures for activating and deactivating the airframe IPS.

c.    Installing a primary or advisory ice detection system.