Desktop Flight Simulators: Simulation Fidelity and Pilot Performance

Behavior Research Methods, Instruments, & Computers 1995, 27 (2), 152-159 Desktop flight simulators: Simulation fidelity and pilot performance DRAKER. BRADLEYand STUARTB. ABELSON Bates CoUege, Lewiston, Maine Improvements in the computing power and visual resolution of modern desktop computing sys tems, as well as advances in software technology for displaying high-speed animations, have en couraged the development of relatively sophisticated real-time flight simulators for the PC and Mac intosh. We review some of the factors that determine how well such programs capture the actual experience of flight. The most significant factor limiting the quality of performance in flying a simu lated aircraft is the "frame rate" problem: at low altitudes and in highly detailed visual environments, as in approaching a runway threshold during landing, the computational demands of the animation may necessitate a reduction in the number offrames displayed persecond on the screen. The delayed sensory feedback that results proves to be very detrimental to sustaining smooth control of the air craft, especially during the flare to touchdown where such control is needed most. This finding par allels the well-known effects of delayed auditory feedback (Lee, 1950) and delayed visual feedback (Smith, 1962). For many aviation enthusiasts, the challenge and ex tion aircraft, at depicting the behavior ofthe various in citement of learning to fly is tempered only by the cost struments in the cockpit, and at displaying a real-time ofinstruction ($6Q-$80lhour). However,recent advances animation ofthe view out the window. Not surprisingly, in hardware and software technology make it possible to desktop simulators focus on modeling the visual experi run highly sophisticated flight simulator programs on ence offlight, since this can be depicted on the computer desktop computers. A flight simulator is a computer pro monitor. Due to hardware and cost constraints, auditory gram that models all ofthe important principles ofoper cues are less frequently modeled, and sensory cues af ating an aircraft in three-dimensional flight. The typical fecting the vestibular and kinesthetic systems are not simulator allows the user to take off, fly the aircraft modeled at all. The realism ofthe visual display contin through a variety offlight configurations (including aer ues to improve, however, and the industry has come a obatics), navigate between way points, and land at a des very long way from initial efforts, which used "wire tination. Some programs allow the user to control the frame" drawings ofbuildings and other objects. Recent seasonal, weather, and wind conditions ofthe flight, the programs such as Microsoft Flight Simulator 5.0 use reliability of the aircraft (so that simulated "emergen photorealistic imaging, cybergraphics, real-time ray cies" can arise), and various other flight parameters, tracing, Gouraud shading, fractal geometry, and other While some simulators are intended only for entertain advanced graphics techniques (Mass, 1993; Pruyn, 1992). ment, others are specifically designed for flight training. The result is stunningly realistic images and real-time Many provide real-world navigation capability using animation performance that rivals that previously seen databases and scenery areas that cover the United States, only on dedicated mainframe systems. In light ofthese Canada, and Western Europe. Major terrain features, advances, the authors became intrigued with the possi such as lakes, rivers, highways, and cities, as well as air bility ofusing desktop flight simulators to promote skill ports and navaids, are provided in the databases. acquisition and positive transfer to the actual flight en Most desktop flight simulators are reasonably good at vironment. Moreover, we see intriguing possibilities for modeling the flight dynamics and "feel" ofgeneral avia- conducting research investigating the acquisition of complex cognitive skills in an ecologically valid setting (i.e., learning to fly and navigate an aircraft). The pres Wethank American Airlines (Dallas), and Lt. Gleysteen, Lt. Stucky, ent paper reviews the strengths and limitations ofdesk and Gary Hensley ofBrunswick Naval Airstation (Brunswick, ME) for top flight simulators from this perspective. providing the authors access to full motion flight simulators (an MD 80 and Orion P-3, respectively). The time spent exploring these simu lators helped the authors to better appreciate the unique contributions How Simulators Work and limitations of desktop flight simulators. We also thank Thomas The reader unfamiliar with flight simulators might Kopke for reviewing this paper and providing comments and sugges wonder how the airplane is flown using a computer. The tions on technical matters. Any errors that remain are the responsibil ity of the authors. Correspondence should be addressed to D. R. pilot employs a mouse, control yoke, joystick, or cursor Bradley, Department of Psychology, Bates College, Lewiston, ME keys to control the pitch and bank of the aircraft, and 04240 (e-mail: [email protected]). various keys on the keyboard to adjust the throttle, gear, Copyright 1995 Psychonomic Society, Inc. 152 FLIGHT SIMULATORS 153 flaps, radios, and so on. The program monitors the in may not represent some aspect of flight realistically is puts from the flight controls, computes their effects on that the underlying theory used in the program is in some the aircraft's attitude, airspeed, altitude, and the like, respect incomplete or incorrect-that is, it fails to accu and then displays these effects on the instruments and in rately describe the real thing. In Microsoft FS 4.0, for the view out the window. This cycle is repeated many example, the aircraft often stalls in an unrealistic fash times each second, so what we see on the computer ion, with the nose pitching up rather than down. Stalls in monitor is a succession of snapshots or frames ofwhat FS 4.0 also fail to show the characteristic shudder asso the view inside and outside ofthe cockpit looks like at ciated with the stall ofa real aircraft. 1 discrete points in time. At a typical rate of 15-30 frames per second (fps), an impression ofcontinuous movement Skill Acquisition on Desktop Simulators of the aircraft through space is achieved. The apparent We have employed flight simulators over the last 3 motion is simply a variant ofthe phi phenomenon (Wert years to teach students a number of useful skills (Brad heimer, 1912/1961). ley, 1993; Bradley & Abelson, 1994). At the most basic In the real world, flying by reference to visual cues level, the task ofsimply flying the aircraft develops im outside the cockpit is conducted under visual flight rules portant perceptual-motor skills. Specifically, the student (VFR), whereas flying solely by reference to the instru must master the intricate feedback relationship between ments is conducted under instrument flight rules (IFR). his or her control inputs (by way ofthe stick, rudder, and There are programs that simulate VFR flight (e.g., Elec throttle) and the resulting changes in the outside visual tronic Arts' Advanced Flight Trainer), IFR flight (e.g., environment and the instruments. Understanding this AzureSoft's ELITE flight simulator), or both (e.g., Mi feedback relationship allows the student to control the crosoft's Flight Simulator 5.0). The most sophisticated aircraft precisely, as in flaring the aircraft to land, per and expensive simulators are those designed for IFR forming aerobatic maneuvers, and staying on the glide flight: AzureSoft's ELITE flight simulator, for example, path when shooting visual or instrument approaches to is sufficiently advanced that the FAA is considering the the runway. Moreover, reading instruments to assess the possibility ofallowing this simulator to be used for flight state ofthe aircraft in a three-dimensional space requires training (Forster, 1991). information-processing skills. Flight in IFR conditions Depending on the sophistication ofthe simulator, sev called blind j7ying-demands the highest level of skill eral techniques may be available for navigating the air in this area, because the pilot must be able to visualize craft. The simplest method, called pilotage, consists of the aircraft in relation to the outside world in the absence comparing visual landmarks seen "out ofthe cockpit" to ofexternal visual cues. Even the relatively simple task of corresponding features on aeronautical charts or maps. flying under VFR conditions in the immediate vicinity With dead reckoning, the pilot navigates by flying spe (or traffic pattern) ofthe local airport requires spatial cific headings on a compass, and by using time and dis orientation skills. The student must develop a clear rep tance calculations to estimate the time between various resentation ofthe airport in relation to nearby landmarks checkpoints. Finally, radio navigation allows the pilot to and constantly monitor his or her position using this navigate using electronic aids, such as VOR (very high cognitive map. Cross-country flying is, of course, even frequency omnidirectional range), ADF (automatic di more demanding and requires the student to master basic rection finding), LORAN (long-range navigation), GPS navigational and computational skills (e.g., how to read (global positioning systems), and ILS (instrument land and use a compass, how to make time and distance cal ing systems). Both dead reckoning and radio navigation culations, how to

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