Transition to Unfamiliar Aircraft
This advisory circular (AC) is intended to help plan the transition to any unfamiliar fixed-wing airplanes, including type-certificated (TC) and/or experimental airplanes. It provides information and guidance to owners and pilots of experimental, simple, complex, high-performance, and/or unfamiliar airplanes. It also provides information to flight instructors who teach in these airplanes. This information and guidance contains recommendations for training experience for pilots of experimental airplanes in a variety of groupings based on performance and handling characteristics. This AC does not address the testing of newly built experimental airplanes. The current edition of AC 90-89, Amateur-Built Aircraft and Ultralight Flight Testing Handbook, provides information on such testing. However, if a pilot is planning to participate in a flight test program in an unfamiliar and/or experimental airplane, this AC should be used to develop the skills and knowledge necessary to safely accomplish the test program utilizing the guidance found in AC 90-89.
Use of Liquid Water Equivalent System to Determine Holdover Times or Check Times for Anti-Icing Fluids
This advisory circular (AC) provides guidance for the Federal Aviation Administration’s (FAA) standard for a Liquid Water Equivalent System (LWES). This AC applies to anyone proposing to design, procure, construct, install, activate, or maintain an LWES. An LWES is an automated weather measurement system that determines the Liquid Water Equivalent (LWE) rate in conditions of frozen or freezing precipitation. The LWE rate is used by the system with the appropriate endurance time (ET) regression equations and regression coefficients specified in an FAA-approved current database at http://22.214.171.124/RegressionInformation.html to determine the holdover time (HOT) or check time (CT) for an aircraft’s applied anti-icing fluid (Society of Automotive Engineer (SAE) Types I, II, III, and IV). Thus, the LWES incorporates a Holdover Time Determination System (HOTDS) or Check Time Determination System (CTDS). The HOT is used to determine how long a fluid would provide protection assuming that the current conditions do not change. The CT is used to determine the fluid’s current protection capability, while incorporating varying weather conditions.