Usability of Light-Emitting Diodes in Precision Approach Path Indicator Systems by Individuals with Marginal Color Vision

Civil Aerospace Medical Institute2014PDFTech ReportMilburn, Nelda J.Gildea, Kevin M.Perry, Deborah L.Roberts, Carrie A.Peterson, LindaCivil Aerospace Medical InstituteUnited States. Office of Aerospace MedicineUnited StatesColor blindnessVision testsLight emitting diodesHuman subject testingApproachLanding aidsFeasibility analysisDOT/FAA/AM-14/6To save energy, the FAA is planning to convert from incandescent lights to light-emitting diodes (LEDs) inprecision approach path indicator (PAPI) systems. Preliminary work on the usability of LEDs by color vision-waivered pilots (Bullough, Skinner, & Milburn, 2012) indicated that red weak (protan) individuals made a fewerrors identifying red. Hence, this follow-up study explored whether clustering LEDs of different chromaticitiesof the same hue would aid users with color vision deficiencies (CVD).Participants, aged 18-33 years, included 45 with normal color vision (NCV). Additionally, 48 were diagnosedusing the Colour Assessment and Diagnosis (CAD) test as 27 deutans (including five subjects with potentialdeutan deficiencies), 11 protans, two tritans, and eight subjects evidencing both red-green and yellow-bluedeficiencies. Participants completed the Dvorine pseudoisochromatic plate test, the Signal Light Gun Test (whichis the secondary test for issuing color vision waivers), the Cone Contrast Test, and a simulation of the PAPIsystem. Participants were asked to name the colors of a 4-light, color-coded PAPI simulation using typical red (R)and white (W) light configurations resulting in five possible patterns (WWWW, WWWR, WWRR, WRRR, andRRRR) composed of either incandescent lights, or clusters of three monochromatic or three heterochromatic5mm cylindrical LEDs.Analyses did not indicate any significant differences between the incandescent, monochromatic, andheterochromatic conditions. A between-group analysis found that a group comprised of those with both red-greenand yellow-blue deficiencies performed significantly worse than all other color vision groups. Performance wasnot significantly different among all other groups. The protan group performed perfectly on all light sources, evenon the 16 trials without comparative color luminance cues.This finding suggests that color vision-waivered pilots will perform the same on red and white LED PAPIsystems as with the current incandescent system.119