This SAE Aerospace Information Report (AIR) provides various graphical displays of atmospheric variables related to aircraft icing conditions in natural clouds. It is intended as a review of recent developments on the subject, and for stimulating thought on novel ways to arrange and use the available data. Included in this Report is FAR 25 (JAR 25) Appendix C, the established Aircraft Icing Atmospheric Characterization used for engineering design, development, testing and certification of civilian aircraft to fly in aircraft icing conditions.

Purpose:

Research on aircraft icing conditions in the atmosphere has been conducted intermittently since the 1940s. But, until recently, only the data gathered during the first few years of flight research had been condensed into extreme value envelopes and publicized for use in the design of ice protection systems for aircraft. One purpose of this AIR is to assemble in one document some new ideas on displaying icing-related variables and using them for various applications.

Field of Application:

This report presents atmospheric data that describes the aircraft icing environment. The report contains four different approaches in displaying and using the data:

Currently Accepted Civil Design Envelopes ("FAR-25, Appendix C").

U.S. Air Force Trial Design Envelopes.

Distance-Based Envelopes.

A Nomogram and Statistical Approach.