Method and apparatus for controlling flare engagement height in

Abstract

Disclosed is a method of and apparatus for determining the flare height at which the flare maneuver of an automatic landing procedure is initiated. The method includes the step of generating an adjusted approach sink rate signal, which depends on the ground speed of the aircraft during a landing approach and is compensated for short term deviations from the glideslope angle. The adjusted approach sink rate signal is filtered (first order lag), and the filtered signal is then used to establish: (a) a nominal flare height value when the aircraft sink rate is between two predetermined sink rate values (the aircraft landing approach speed is in a nominal range); (b) a flare height that is above the nominal flare height value and is linearly related to the adjusted approach sink rate of the aircraft when the adjusted approach sink rate exceeds the first predetermined value (relatively high ground speed approach); and (c) a flare height that is less than the nominal flare height value and is linearly related to the magnitude of the adjusted approach sink rate signal when the magnitude of the filtered adjusted approach sink rate signal is less than the second predetermined sink rate magnitude (relatively low ground speed approach). In the disclosed arrangements, provision is made to limit the flare height determined by the invention to maximum and minimum flare height values and provision is made for storing the flare height signal for use by the automatic landing system after the flare maneuver has been initiated.