Tactical Symbology Standards

Abstract

CRT displays aboard U.S. Navy ships use a standardized monochrome Naval Tactical Data System (NTDS) symbol set to represent properties of symbols such as platform type (e.g. Aircraft Carrier, Combat Air), environment (e.g. air, surface, subsurface), and identification (e.g. hostile, friendly). A color symbol set has been proposed in NATO Standardization Agreement 4420, Display Symbology and Colours for NATO Maritime Units (1990). The U.S. Navy is currently considering ratification of this Standardization Agreement (STANAG). Empirical comparisons of operator performance using the NTDS symbology versus those using the color-filled NATO STANAG symbology were conducted. Two additional experimental symbologies were also created. The first, called NTDS Equated, is a color version of the NTDS symbol set, and the second experimental symbol set, called NATO Outline, is a color outline version of the color filled NATO STANAG symbol set. Test subjects were asked to find (hook) specific symbols during a tactically relevant scenario.

Time to the first correct hook and percentage of correct hooks were subjected to analyses of variance (ANOVA). Experimental results revealed that the NATO STANAG symbol set outperformed all other symbol sets in terms of symbol recognition time, and outperformed the NTDS Standard symbol set for symbol recognition accuracy as well. The results indicated that tactical information can be transferred more quickly and accurately to watch standers through effective use of symbol coding. Test subjects familiar with the NTDS symbology expressed a preference for the color symbol sets in opinion surveys administered after the experiment. General conclusions resulting from comparisons across symbol sets were that color fill was more effective than color outline, and that operator performance gains were achieved as a result of color coding and greater information content on the symbol. This paper presents the human performance assessment that was conducted, the results, and the implications of the findings for ratification of NATO STANAG 4420.