Purpose and Scope: The objective of this Minimum Operational Performance Specification is to specify the minimum performance of onboard inflight icing detection systems. Throughout the document@ these devices are referred to as Flight Icing Detection Systems (FIDS). These systems are intended to either provide information which indicates the presence of ice accreted in flight on monitored surfaces or indicate the presence of icing conditions in the atmosphere. They may operate the airplane anti-ice/deice systems. Detection of ice accreted on the ground is not considered in this document but can be found in ED-104. This MOPS was written for the use of FIDS on airplanes only@ as defined in paragraph 1.5. Use on other aircraft may require additional considerations. Chapter 1 of this document provides information required to understand the need for the equipment characteristics and tests defined in the remaining chapters. It describes typical equipment applications and operational objectives and is the basis for the performance criteria stated in Chapter 2 to Chapter 4. Definitions essential to proper understanding of this document are also provided in Chapter 1. Chapter 2 contains general design requirements for an onboard FIDS. Chapter 3 contains the Minimum Operational Performance Specification for the equipment@ defining performance under icing conditions likely to be encountered in flight. Chapter 4 describes the environmental test conditions which provide a laboratory means of determining the overall performance characteristics of the equipment under conditions representative of those which may be encountered in actual operations. Chapter 5 describes recommended test procedures for demonstrating compliance with Chapter 3. Chapter 6 specifies the performance required of the installed equipment. Ground and flight tests for the installed equipment are included when performance cannot be adequately determined through testing under standard test conditions.