TCAS II pitch guidance control law and display symbol

Abstract

An airplane pitch guidance control law and display symbol for a Traffic alert and Collision Avoidance System (TCAS) is disclosed. The control law converts a TCAS computer-generated vertical air speed command into a pitch guidance command. The pitch guidance command controls the location of a symbol (51) on the pitch axis of an electronic attitude display (21) that guides a pilot toward a pitch attitude that will result in a vertical speed that eliminates a collision threat. The preferred symbol is a pitch axis leg (53) and a pair of outwardly diverging legs (55a, 55b). The pitch axis leg (53) defines the minimum climb or descent attitude required to achieve a safe climb or descent angle. The pitch axis leg (53) and the diverging legs (55a, 55b) combine to define a climb or descent attitude range to avoid. The distance between the pitch axis leg 53 and the boresight 39 of the airplane symbol of the display is controlled by a RA.sub.CMD signal produced by: subtractively combining the vertical speed command (V.sub.STCAS ) produced by a TCAS II computer and the vertical speed of the airplane (V.sub.SIND); multiplying the result by a sensitivity factor K whose value is related to the true air speed of the airplane and 57.3 to approximate the arc tangent of the quotient; and subtracting a factor that compensates for the fact that flight path angle changes lag pitch attitude changes.

Dependencies are inferred from the claim text.