GB830043A - Improvements in or relating to visual flying aids - Google Patents

Abstract

830,043. Visual landing aids for aircraft. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 22, 1958 [Jan. 23, 1957], No. 2409/57. Class 118 (2). [Also in Group XI] An angle of approach indicator for aircraft comprises two beams of light each divided about a medial plane into two contrasting portions to produce three different indications according to whether the aircraft is in a zone between the two medial planes or outside the zone in one sense or another. In Fig. 2, the optical device for producing the divided beam comprises a light source L from which a beam of light is focused upon a slot O in an opaque screen S. A red filter F is disposed between the light source and the slot so as to extend halfway across the beam and an opaque bracket U minimizes the amount of mixing of the red and white beams at the plane of division. In Fig. 1, a glide path indicator comprises two such optical devices positioned at points A and B along the runway, the division planes being indicated by the lines A-A<SP>1</SP>, B-B<SP>1</SP>. An aircraft approaching the runway will see two white, one white and one red or two red lights depending on whether it is above, within, or below the zone defined by the planes A-A<SP>1</SP>, B-B<SP>1</SP>. In a modification, the devices may each comprise a row of lights extending perpendicular to the runway, and in another modification (Fig. 5, not shown) the devices A may be mounted vertically above the devices B, and further rows may also he used to define intermediate zones. The contrast between the two halves of the beam may be in two or more respects, e.g. colour and intermittency for one part, and continuous white for the other.