Protans and PAPI: Recognition of a two colour code by persons with defective colour vision

摘要: In some countries there is controversy as to whether normal or near colour vision necessary for pilots of aircraft. It has been argued that information displayed by aviation codes always redundantly and in modern less dependence on acquired visually from outside the One signal system displays solely coding Precision Approach Path Indicator (PAPI) which signals an approach land too high low means number red white signals. A Farnsworth lantern was modified simulate PAPI viewed one nautical mile under conditions close 1.5 km visibility. Normal observers were able identify distinguish them blank without difficulty except subjects made a few errors confusing yellowish (simulating attenuated atmosphere) with red. Most defective white, protan frequently failed see signal, calling it blank. Although protans could colours error concluded majority are not red/white reliably despite code being simple two category fact brightness differences between available cue. The results surprising since past reports suggest defectives recognise only so might have expected be within their capacity. = deutans also surprising.