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Demanding situations push people to their physical limits. Few situations make more demands than that of flying a modern combat aircraft, which requires a combination of prolonged concentration and split-second decision making. Feeding the pilot critical information as quickly as possible presents the greatest challenge given that even the most highly trained pilot has a fixed bandwidth for processing visual information.
The myriad dials and gauges of the modern cockpit relay a plethora of mission-critical information. To read one of those gauges, you must localize your vision to within a thumbnail's width at arm's length because central vision—the area in which you can read letters and numbers—encompasses only two to four degrees. More important, it takes one-fifth of a second for each eye movement, not counting the time it takes to process that information.
The traditional cockpit display shown in Figure A has six-plus gauges and would therefore take considerably more than a second simply to scan the information it displays. Yet the pilots of modern combat aircraft rarely have the luxury of devoting a full second and more just to read their instruments.
Figure A. IHMC's radical departure from traditional dial-and-gauges cockpit displays is apparent in a side-by-side look at OZ (left) and Microsoft's Flight Simulator (right). OZ combines all the instrumentation data from the traditional display into one graphical interface.
David Still and colleagues work on new cockpit displays to overcome this basic human limitation. Still participated in earlier research at Indiana University with Larry Thiobos, who discovered that existing models on the limits of human central and peripheral vision missed the mark by an order of magnitude or more, depending on the stimulus type involved. Although the accepted limit on the scope of central vision still holds, given the proper framework our eyes can detect 10 times more detail than current thinking accepts. Thus, we can tailor the stimulus to take advantage of the sensory system's natural filtering and processing capabilities, and we can manipulate the data so it provides exactly what we need to know at any particular time.
Figure B shows the OZ cockpit display, which combines the traditional display into one graphical interface that lets a pilot perceive in a tenth of a second the different data streams shown on the gauges in Figure A. The interface presents a twofold symbology, superimposing an aircraft metaphor on a star field metaphor. The coordinate system provided by the star field brings the outside world into the aircraft and provides pitch, roll, altitude, and drift information. The aircraft metaphor dynamically adjusts to indicate performance capabilities based on current environmental conditions and aircraft configurations. These performance capabilities include flight path options, power requirements, and configuration information as shown in Figure C.
Figure B. Aircraft metaphor imposed on a star-field metaphor: Star
layers mark every 500 feet in altitude, and each star layer's edge is
placed 10 degrees apart, so that star streams originate from every
third star and mark 30-degree heading increments.
Figure C. Actual Oz display. The runway (three green dots) is 30
degrees to the left of the aircraft centerline, and the plane is
gradually turning left toward it at 2,900 feet. Current heading is 081
degrees, and highlighted heading is set on the runway heading of 092
degrees.
The display system does most of the pilot's computing for him or her and adjusts the display to provide key information about the state of the aircraft in a way directly "seeable" by the human visual system, which makes the aircraft a natural extension of the human perceptual system. For example, the relationship between airspeed, lift, drag, and attitude is so complex that pilots generally learn simple rules of thumb to figure out what to do, even when they have read all the dials. OZ figures this out and displays the information in simple geometric relationships between shapes. All the pilot has to do is keep some lines aligned: One can "see" the extent to which the aircraft responds to the controls, and this relationship is preserved in the visual structure of the display even as the relationships change with changing airspeed, attitude, the lowering of flaps, and so on. The interface also makes full use of a pilot's visual system so that when phenomena such as blinding light temporarily diminish central vision, the pilot can still process instrumentation information and fly the plane.
In another endeavor, IHMC's Anil Raj collaborates with the Naval Aerospace Medical Research Laboratory to explore an avionics-and-information data display that uses haptics to exploit the sense of touch. Whereas flying a plane tends to overload a pilot's visual and aural channels, Raj and colleagues have found that tactile channels remain underused and offer spare capacity for receiving spatial information. The Tactile Situation Awareness System (TSAS) consists of an array of pneumatically activated tactors applied in columns and rows to the torso. These tactors provide intuitive 3D information to aircrew, astronauts, and those who control remotely operated vehicles. Intuitive delivery of orientation, velocity, and range has been proven in actual TSAS flight tests. Navy helicopter pilots wearing the TSAS flight vests shown in Figure D while operating fixed- and motion-based simulators have demonstrated decreased reaction time, increased maneuvering precision, and decreased perceived workload when receiving tactile cues in addition to normal visual, audio, and motion information. Flight tests in fixed and rotary wing aircraft have proven that haptic displays can supplement cockpit displays and external cues to improve situation awareness in flight. Further, in test situations that exclude visual information, TSAS has successfully supplanted pilot visual systems(1).
Figure D. Navy helicopter pilots wearing the TSAS flight vests (shown
in the lower left) while operating simulators have demonstrated
decreased reaction time, increased maneuvering precision, and
decreased perceived workload when receiving tactile cues.
(1) 1. A.K. Raj , S.J. Kass and J.F. Perry , "Vibrotactile Displays for Improving Spatial Awareness,"Proc. IEA/HFES 2000 Congress, Int'l Ergonomics Association, Human Factors & Ergonomics Society, Santa Monica, Calif.,pp. 181-187.
