On behalf of my Company, which manufactures the RAE Head-up Display Equipment referred to in K. J. Holden's paper in the December 1964 issue of the Journal (pp 833-6), I would like to correct some misunderstandings which seem to exist and to amplify certain statements in this otherwise interesting and informative contribution to the techniques of instrument displays.

Dr. Holden states: “The essence of the (RAE) display is an attempt to reproduce the appearance of the runway as it would appear to the pilot.” This statement is incorrect as the flight director symbol to which he refers, is made up of a “target spot” (a’) and associated director lines (a) in Fig. 1. This symbol is a pure integrated flight director and is not and never has been intended to represent the runway.