It also discusses when an ultralight must be operated as an aircraft under the regulations applicable to certificated aircraft.

Provides guidance for the operation of ultralight vehicles in the U.S. Information includes airport and flight park operations, how to work with ATC, and the availability of weather services.

This AC provides suggestions and safety-related recommendations primarily to assist amateur-built aircraft and ultralight vehicle builders in developing individualized flight test plans.

The current edition of AC 90-89, Amateur-Built Aircraft and Ultralight Flight Testing Handbook, provides information on such testing.

It recommends traffic patterns, communications phraseology, and operational procedures for use by aircraft, lighter-than-air aircraft, gliders, parachutes, rotorcraft, and ultralight vehicles. This AC stresses safety as the primary objective in these operations.