Design of Instrument Approach Procedure Charts Comprehension Speed of Missed Approach Instructions Coded in Text or Icons
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Design of Instrument Approach Procedure Charts Comprehension Speed of Missed Approach Instructions Coded in Text or Icons

Filetype[PDF-3.26 MB]

  • English

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    • Edition:
      Final Report July 1991-December 1991
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    • Abstract:
      Instrument approach procedure (IAP) charts are often cluttered and confusing. The quantified effects of chart design

      changes on information transfer are needed by chart manufacturers to make changes uhich will enhance information transfer

      and human performance. The present study was conducted as part of a continuing effort at the Volpe National

      Transportation Systems Center Human Performance Laboratory to develop human performance-based design guidelines for IAP


      The objectives of this experiment were to determine whether encoding missed approach instructions in text or icons would

      result in more efficient information transfer, and if the information transfer efficiency for either coding technique was

      dependent upon the level of information content. Twelve pilots currently licensed for instrument (IFR) flight

      participated as subjects. Text instructions were either taken directly or developed from instructions found on National

      Ocean Service (N0S) IAP charts. Because of formatting inconsistencies in current NOS missed approach instructions, a

      standard format was developed. In order to approximate the range of information content found in current NOS missed

      approach instructions, these instructions possessed one of three levels of information content: low, medium, and high.

      Comprehension speed was measured by counting the number of one second presentations (glances) subjects required to view

      the instructions in order to verbally report them. Report accuracy was also measured. Subjects completed questionnaires

      concerning their flight experience, preferences for IAP chart manufacturers, and preference for text or iconic coding of

      the instructions.

      Across the range of information content levels, iconic missed approach instructions were comprehended more quickly and as

      accurately as instructions coded in text of the font style and size used by NOS. Regardless of coding technique, report

      accuracy was significantly worse for instructions with a high information content level. Subjects indicated a strong

      preference for using iconic missed approach instructions in single pilot IFR conditions.

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