The following papers were presented at a meeting of the Institute held in London on 12 March 1965. Mr. W. P. Davies (Polhemus Associates) first outlines the height measurement requirements for a supersonic transport aircraft. The other speakers review the available techniques: Mr. R. Whalley (Ferranti) dealing with inertial techniques, Mr. B. Cape (S. Smith & Sons) with pressure measurement techniques and Mr. W. L. Garfield (Standard Telephones and Cables) with radio altimetry. Mr. G. E. Beck (The Marconi Company) describes a recently developed radio altimeter.

1. Introduction. In outlining requirements for height measurement in supersonic transport aircraft it should first be said that not all the requirements are special to supersonics. Some of the requirements are the same as already exist, or will exist in the 1970's, for subsonic aircraft. The main problem in supersonic aircraft will be to maintain the same accuracy over increased measurement ranges of height and height rate and in an environment of higher speeds and temperatures. Where-ever possible then, the requirements are of the same standard expected for subsonic aircraft of the 1970's. More stringent requirements are stated only where they are considered necessary; there are enough real problems in the advance to civil supersonic operations without creating artificial ones.