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.