The Touch‐Down Rate‐of‐Descent Indicator: An Instrument Developed by North American Aviation for Use in Measuring Impact on Landing

DURING acceptance tests of aircraft, one of the basic data required is the rate of descent. The required information is a vertical component of the rate of descent just prior to touch‐down on a landing surface. These data are used as an aid in determining the impact imparted to the landing gear, as well as to other structures of the plane. Rate of descent information is also used during training of both military and commercial pilots. A pilot is interested in knowing immediately after touch‐down the rate of descent of his aircraft, so that he can associate his control settings and his psychological attitude with the data given him. The touch‐down rate of descent information is also important when hard landings aboard an aircraft carrier are considered. The deck of the carrier presents a second moving object with which to contend; therefore the rates of descent will be even more unpredictable and, in most cases, of higher values.