This document provides information regarding ice detector technology, design and operating requirements. The SAE document SAE AS 5498 provides detailed information regarding the requirement, specifications, qualification, and certification of icing detection systems. This document is not meant to repolace SAE AS 5498 but to enhance it by considering unique aspects of sensing technology and in particular those that may not be certificated at the time of this revision. To that end an effort has been made not to duplicate information contained in SAE AS 5498. Icing rate information is included where applicable. The primary application is associated with ice forming on the leading edges of airfoils and inlets while the aircraft is in flight. Information related to detection of ice over cold fuel tanks and icing at low velocity operation is included. The material is primarily applicable to fixed-wing aircraft. Unique requirements for engine inlets and rotorcraft are also provided. The purpose of this document is to provide information regarding various in situ icing sensing technologies and issues a user of these technologies should consider regarding the method of operation, performance, design, verification, and installation of aircraft ice detectors and icing rate indicators. The intent is not to duplicate SAE AS 5498 but to supplement it in areas that may not have been deemed appropriate for such a standards document.