A series of VOR-DME instrument landing approaches was flown in the Langley DC-9 Full-Workload Simulator to compare pilot performance, scan behavior, and workload when using a counter-drum-pointer altimeter (CDPA) and a digital altimeter (DA). six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. The DA consisted of five, seven-segment LED digits, 0.28 inch high. pilot scanning data were collected with an oculometer system. The

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... data were reduced to dwell percentages, average dwell times, transition matrices, and dwell time histograms and were statistically analyzed. In addition to the pilot scanning parameters, flight performance and subjective opinion data were collected and evaluated. Based upon the results of these tests the following conclusions were drawn. The processes of gathering information from the CDPA and the DA are different. The DA imposes a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altimeter data after looking away from the altimeter was more evident with the DA than with the CDPA. And" finally, all the pilots preferred the CDPA over the DA.