An experimental comparison of five different attitude indicators.

Abstract

Two -s-udies-were conducted in which five simulated aircraft attitude indicators,,representing three different indicating principles, were compared.Tw6v*,dicators were of the "earth reference" type, in mhich the moving element repres'ented the horizon as on the conventionalAatititude indioator. Two indicators were of an "airplane reference" type, which presented aircraft rather than horizon movement.Thqe fjfth indicator provided a "stabilized sphere" type of ýpresentatidn,. Tests Vere miad4 in a C-9 Link Trainer and records were performanceflight maneuvers reversals~following sifolotednrorgh iir gusti, anda pilot preferences.Major interest centered around comparison of the "earth reference" and "airplane reference" principles of attitude indication, since these provide opposite directions of movement on the indicator.Each of the five indicators was flown kry Air Force pilots, eight different pilots per instrument.In-additon, itwo indicators representing the two opposed types, were flown by college students with no prior flight experience.The Air Force pilots used in this study were highly experienced on the earth reference type of indicator, and had not previously flown indicators using the airplane reference principle. For this reason, apparently, they made more aileron reversals on the airplane reference type indicators. In the pitch dimension, however, t,)ey made slightly, but not significantly, fewer control reversals o4 thes'e/ idicators. Moreover, their preferences somewhat favored the unfamiliar airplane reference indicators.For the college students, both the control reversal and preference data favored the airplane reference principle. PUBLICATION REVIEW(This report has been reviewed and is approved.

What Moves, the Airplane or the World. A Review of the Motion Relationship Problem in Presenting Aircraft Attitude and Guidance Information

“…In the first of two studies, the later of which was discussed previously, Gardner and Lacey (1954) compared five different motic.n relationships ;n attitude indicators. The five instruments used were: (I) a conventional moving horizon display, (2) an experimental moving aircraft display, (3) a sphere stabilized with respect to the earth's surface, (4) a reversed pitch stabilized sphere, the same as (3) except that the pitch indication was reversed, and (5) a semi-three-dimensional moving aircraft display in which a cross section of an aircraft's wing moved behind a pivoted cross section of the tail.…”

“…One of the most unrealistic studies citc I was that of Gardner (1954). This was a laboratory experiment in which the experimenter set the attitude presentatioi from the back of the display, and the subject verbally announced the control movement necessary to correct the situation.…”

“…The widely used Air Force ID-249, shown in Figure 3, is a frequency separated display in which the aircraft's slowly changing displacement from selected course is presented inside-out, while the aircraft's more rapidly changing heading relative to the selected course is presented outside-in. The Lear LIFE display system shown in Figure 4, which accompanied the L-102 autopilot and was adopted by a few local service airlines flying the (Browne, 1952;Gardner, 1954;Gardner and Lacey, 1954) found different results when experienced pilots, as opposed to novice pilots or non-pilots, were used.…”

Visual presentation of information.

“…The airplane reference or 'fly from' type of indication is the easiest to learn to use and interpret. * (Browne, 1945;Loucks, 1947;Gardner, 1954. ) •*Most current aircraft gyro horizon or attitude indicators are of the earth reference type and give a 'fly to' indication.…”