Flight Test of Diamond and Other Proportioned Runway Paint Markings for Glide Slope Guidance

The glide slope guidance value of three patterns of specially proportioned paint markings on the approach end of a small airport  runway was evaluated in a flight test which also included approaches using a red/white VASI and approaches using only normal visual cues.  Both private and professional pilots were instructed  to approach on a glide slope such that the special paint markings, a diamond, an ellipse, or a pair of rectangles, appeared square or of equal dimensions in length and width.  Results indicated that approaches made with the specially proportioned paint markings were similar to approaches made using only normal cues.  While flight performance appeared to be unaffected by providing any of the special paint markings, approaches made using the red/white VASI were less variable.  It is concluded that there is no evidence of improved performance supporting the previous claims that squareness judgments of runway paint markings provide significant aid in glide slope control.  Additional tests conducted with diamond marks designed to provide a square image from 3 degrees to 5 degrees produced results indicating large errors in the undershoot direction.