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Utility of Motion and Motion-Cueing to Support Simulated In-Flight Rotary-Wing Emergency Training Derek L. Pasma, Stuart C. Grant, Murray Gamble, Ronald V. Kruk and Chris M. Herdman Proceedings of the Human Factors and Ergonomics Society Annual Meeting 2011 55: 133 DOI: 10.1177/1071181311551028 The online version of this article can be found at: http://pro.sagepub.com/content/55/1/133

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PROCEEDINGS of the HUMAN FACTORS and ERGONOMICS SOCIETY 55th ANNUAL MEETING - 2011

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Utility of Motion and Motion-Cueing to Support Simulated In-Flight Rotary-Wing Emergency Training Derek L. Pasma1, Stuart C. Grant2, Murray Gamble1, Ronald V. Kruk3, Chris M. Herdman1 1

Carleton University; 2 Defence Research and Development Canada; 3 Ravenmark Consultations, Inc.

The aim of the current study was to evaluate the utility of three flight simulator motion conditions (fixed-base, motion-cueing seat, and full-motion) to support training of in-flight rotary-wing emergency recovery procedures. Military helicopter pilots were randomly assigned to two of three possible motion configurations and subject to three in-flight emergencies. Pilot handling ratings indicate wide acceptance of the training device in each of the three configurations. Subjective workload assessments showed no difference between motion configurations. Results will be discussed with reference to the importance of pilot simulator acceptance during flight training.

Copyright 2011 by Human Factors and Ergonomics Society, Inc. All rights reserved DOI 10.1177/1071181311551028

INTRODUCTION While the benefit of flight simulator training cannot be disputed, disagreement continues regarding the benefit of motion systems in simulation-based flight training. For example, the Federal Aviation Administration (FAA) requires that full flight simulators used for the highest level of training and evaluation to have full platform motion. However, the additional benefit of simulator motion platforms has not been empirically demonstrated (Burki-Cohen, Sparko, Jo & Go 2009; McCauley, 2006). A number of possibilities exist which can help explain these findings. For example, past motion simulators have suffered from technological limitations that have prevented them from accurately simulating aircraft movement (Hall, 1989). Second, there is great difficulty in conducting methodologically sound transfer of training experiments. This would entail training groups of pilots using simulators with various motions systems and comparing their performance in the real aircraft; a task that is beyond financial and material resources of many researchers. Consequently, the failure to find consistent benefits of motion platforms may be due to a lack of statistical power in methodologically sound experiments. Another possible explanation could be that there is no benefit of motion in simulator-based flight training. The human body is able to sense motion through visual, tactile, kinesthetic, and vestibular senses. The logic behind the argument for motion is that the visual system alone cannot be relied on to effectively cue motion in many situations. Therefore, the addition of short-onset kinesthetic and vestibular motion provides motion onset cues. The visual system then takes over and simulates the sustained motion beyond the

magnitude to which the machine actually moves. This motion is argued to accurately represent the motion of the actual aircraft, allowing for more effective transfer of skills than in a fixed-based system. Moreover, motion is proposed to be more beneficial in rotary-wing flight training than fixed-wing flight training given the inherently unstable nature of the aircraft (Hall, 1989). However, empirical studies have not consistently found that pilot performance benefits from including motion in the simulation. Furthermore, the few transfer of training studies that have been conducted do not find support to suggest that skills learned in a motion simulator transfer to the real aircraft better than those learned in a fixedbase simulator (McCauley, 2006). Dynamic Seat Motion Cueing More recently, initiatives have been undertaken to find more economical alternatives to large, expensive full-motion flight simulators. One alternative has been the integration of dynamic motion cueing seats to provide motion cueing on fixed-based simulators. As such, the dynamic seat takes the place of the full 6degree of freedom (DOF) platform and is responsible for providing the quick onset motion cues to the pilot. Technological limitations prevented widespread acceptance of early motion seats. However, recent advances have addressed many of these limitations and empirical findings suggest that pilot’s preference and acceptance for motion cueing seats is similar to that of full motion platform (Burki-Cohen et al., 2009). In a comparison of full motion and motion cueing in a commercial fixed-wing simulator, no noticeable performance differences were found (e.g., heading deviation) despite slightly faster control reaction time to



certain stimuli (e.g., engine failure) in a full-motion condition. Moreover, when pilots were tested in a quasitransfer condition, no performance differences were found between pilots who were taught in a full-motion condition compared to a motion cueing condition (Burki-Cohen, Sparko, & Jo, 2007). Motion cueing seats have been proposed to improve training effectiveness and performance of various rotary-wing maneuvers and emergencies (Sutton, Skelton, & Holt, 2010).

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PURPOSE The purpose of this study was to examine the ability of different motion cueing technologies to support the training and execution of emergency procedures in rotary-wing aircraft. Using three different motion-cueing conditions (fixed-base, full-motion, and motion-cuing seat), subjective aircraft handling and workload ratings were measured in three emergency scenarios.

Emergency Procedure Training

METHOD

In many situations, the fidelity requirements of the simulator are likely to depend on the specific task and application for which it is to be used. The application of the current research was emergency procedures training. An important distinction for the present study is the nature of the aircraft motion that is represented in an emergency. Gundry (1976, as cited in Hall, 1989) has distinguished between two types of motion: disturbance motion and maneuver motion. According to Gundry, maneuver motion constitutes motion that is the result of control input of behalf of the pilot. Disturbance motion, on the other hand, refers to motion of the aircraft that is beyond the control of the pilot, such as turbulence, wind shear, or a failure of a component of the aircraft (e.g., airframe or engines). Hall (1989) has argued that simulator motion allows for quicker and more accurate detection and correction of disturbance motion because the additional motion cues provide the pilot with more rapid and relevant cues than can be obtained visually. This becomes particularly important when the emergency requires prompt pilot action. The present study tested pilot simulator acceptance and workload in three emergency scenarios: a tail rotor failure, an automatic flight control system/aircraft stability equipment (AFCS/ASE) failure, and an engine failure, each of which fit into Gundry’s disturbance motion classification given that they were caused by factors external to pilot control. However, they also varied in the level of immediate corrective input required by the pilot. For example, at the moment of the tail rotor failure, the aircraft yawed substantially to the right, requiring corrective action from the pilot. In addition, the engine failure while in a hover resulted in an immediate loss of altitude and required immediate pilot response. The AFCS/ASE failure, however, did not result in substantial disruption of aircraft position but required immediate control on behalf of the pilots. According to Hall’s assumption that simulator motion cues are important recognizing and reacting to disturbances that require prompt pilot action, pilot reaction to these emergencies should benefit from motion and motion-cueing technologies.

Participants Twenty-four Canadian Forces helicopter pilots (one female) ranging in age from 25 to 52 participated in the present study. Pilots were recruited from various operational communities, including maritime, tactical, and search and rescue (SAR) and had flight experience on a variety of rotary-wing aircraft, such as the CH149 Cormorant, CH146 Griffon, and CH124 Sea King. There was considerable variation in flying experience, with total rotary-wing flight hours ranging from 110 to 6500 hours (M = 1802, SD = 1833). Not all participants had experience flying medium-lift helicopters and six participants had experience flying the CH149. Apparatus High-fidelity helicopter flight training device (FTD): The present research was conducted using an experimental high-fidelity helicopter FTD. The FTD was designed as part of a collaborative effort between the Canadian Department of National Defence (DND), CAE, Inc., and the Visualization and Simulation (VSIM) Center at Carleton University. The medium lift helicopter FTD was designed to represent the Canadian Air Force’s CH149 Cormorant SAR helicopter. The FTD is a full motion, 6-DOF training device outfitted with high fidelity flight controls. The visuals are provided by four 60-inch high-definition (1080p) LCD TVs and two 42-inch high-definition (1080p) LCD TVs and were driven by state of the art Genesis RTX software. The FTD used an open simulation architecture, which allows for manipulation of simulated aircraft systems and the creation of mission-specific environments. A dynamic motion cueing seat was used for the motion-cueing condition. The seat is capable of linear movement in three dimensions, providing motion cues for sway (lateral motion), heave (vertical movement), surge (longitudinal acceleration), and rotation about the longitudinal axis to provide roll. Combining these movements, the seat is able to provide cueing with four



degrees of freedom. As such, the dynamic seat was designed to produce haptic cues to the pilot, providing kinesthetic sensations that simulate motion but not providing vestibular motion cues. The FTD was designed to allow for easy exchange between the original CH149 seat (used for the fixed-base and fullmotion condition) and the dynamic motion seat. Procedure Participants were assigned to complete the experimental tasks in two of three possible configurations: fixed-base, full-motion, or motioncueing. Pilots were briefed on the emergency they would encounter and the associated procedures they were to execute. They were told that their role would be that of the flying co-pilot and that they would be taking instructions from the non-flying pilot instructor. The non-flying pilot instructor was seated at an instructor station near the FTD and communicated via the simulated aircraft intercom system. Pilots were instructed that they were to recognize and verbally report the emergency, and regain and maintain control of the aircraft. After being familiarized with the simulator, pilots performed each in-flight emergency three times in their assigned motion condition. Pilots performed the tail rotor failure first, followed by the AFCS/ASE failure, and the engine failure last. This order was constant for all participants. After each set of emergencies, participants completed an assessment battery where they provided subjective evaluation of workload and simulator handling qualities. After a one-hour lunch break, participants repeated the procedure in a different motion condition. The order of the motion conditions was counterbalanced across participant. Emergency Scenarios Each pilot was briefed on the emergencies that they would encounter. A description of each in-flight emergency is included below. Additionally, the nonflying instructor pilot (seated at an instructor station near the FTD) walked each pilot through the appropriate emergency checklist (where appropriate). All scenarios were conducted in VFR condition with calm wind conditions. Tail Rotor Failure. A tail rotor control seizure was introduced during forward flight in a low pitch setting. A runway was available for landing. Pilots were required to recognize the tail rotor problem and identify it as being a fixed-pitch malfunction. Pilots were to set up for a straight-in approach and run-on landing and were required to maintain lateral control upon touchdown and

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ground roll. The scenario ended when the aircraft came to a halt on the ground. Automatic Flight Control System (AFCS)/Aircraft Stabilization Equipment (ASE) Failure. During transition at night to a hover over a boat for a hoisting operation, both AC generators fail, causing DC essential bus operation only. As a result, primary flight display panels were blank and all AFCS and stability augmentation support was lost. Pilots were required to use analog backup instruments to immediately establish safe flight and to transition to approximately 5-degrees nose down attitude, initiate and maintain a climb, and ensure increasing airspeed. The scenario ended after the pilot had regained control of the aircraft and flown the recovery profile for one minute (the period of time that would typically be required to start the Auxiliary Power Unit (APU) and restore partial AC power). Engine Failure/Off-Level Landing. In this emergency, one of the three engines failed during a hoisting operation in a confined area. This necessitated an off level landing directly below the aircraft hover position. The pilot was required to maintain horizontal control to ensure that the aircraft did not drift into nearby obstacles while controlling rate of decent to minimize vertical and lateral load on touchdown. Upon touchdown, pilots were to maintain position, minimizing downhill roll and establish a safe, flat pitch resting state on the ground. Measures Workload was assessed using the NASA-Task-Load Index (NASA-TLX; Hart & Staveland, 1988). On a one hundred-point scale, pilots rated the extent to which each of six dimensions of workload was taxed in the execution of the maneuver. They then made 15 dichotomous ratings of which of two dimensions of workload were most influential to their perceived workload. This provides relative weights of each dimension of workload. The handling qualities of the FTD were assessed using the Cooper-Harper Handling Qualities Rating Scale (HQRS; Cooper & Harper, 1969). The HQRS required pilots to rate the handing ability of the aircraft (FTD) by providing a numerical score ranging from 1 to 10. A rating of ‘1’ indicates excellent performed with no need for improvement. A rating of ‘10’ is given to an aircraft that displayed major deficiencies and was not controllable for some or all of the required operation. Physical well-being was assessed with the Simulator Sickness Questionnaire (SSQ; Kennedy, Lane, Berbaum, & Lilienthal, 1993). The SSQ was administered at the beginning of the day and after the lunch break, and after exposure to each motion condition. Pilots were explicitly



informed that they could take a break at any time should they feel the need to do so. RESULTS Pilots rated each motion configuration favourably, providing mean Cooper-Harper ratings of 2.48 (SD = 1.19), 2.43 (SD = 1.21), and 2.34 (SD = 1.26) for the fixed-base, motion-cueing, and full-motion configurations, respectively. A 3 (motion configuration: fixed-base, motion-cueing seat, full-motion) x 3 (emergency: tail rotor failure, AFCS/ASE failure, engine failure/off-level landing) analysis of variance (ANOVA) revealed no significant main effects of motion configuration, F (2, 129) = .175, p = .840, or emergency type, F (2, 129) = .098, p = .907, on pilot HQR.

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significantly lower SSQ scores pre-testing/post break (M = 3.27, SD = 5.96) compared to the full-motion condition SSQ (M = 15.07, SD = 18.12), but not compared to the fixed-base (M = 13.67, SD = 23.28) or motion-cueing (M = 11.54, SD = 16.71) conditions. No differences between the motion conditions were significant.

Figure 2. Mean SSQ scores for baseline and motion configurations.

DISCUSSION

Figure 1. Mean NASA-TLX scores for each motion condition and emergency task.

Self-reported workload was assessed using the NASA-TLX. Mean total NASA-TLX scores (Figure 1) were highest for the motion-cueing seat condition (M = 48.69, SD = 19.42) followed by the fixed-base and fullmotion conditions (M = 43.96, SD = 17.42 and M = 43.90 SD = 15.74, respectively). A 3 (motion condition) x 3 (emergency) ANOVA revealed no significant main effect of motion condition, F (2, 135) = 1.233, p = .295. However, a main effect of emergency was found, F (2, 135) = 3.890, p = .023. A Tukey’s post hoc test revealed significantly higher total NASA-TLX scores for the AFCS/ASE failure (M = 50.98, SD = 20.76) than the engine failure/off-level landing (M = 41.58, SD = 17.61). Mean SSQ scores are presented in Figure 2. A oneway ANOVA (four levels: pre-testing/post break, fixedbase, motion-cueing seat, full-motion) revealed a significant effect of simulation sickness symptoms, F (3, 144) = 3.796, p = .012. Post hoc testing reveal

Cooper-Harper HQRSs indicated that the FTD developed for the current study was received favourably by pilots and supported the recovery training of the three in-flight emergencies that were tested. Cooper-Harper ratings ranging from 1-3 indicate that pilots believed that FTD supported their task in a manner that was satisfactory and not in need of improvement. The mean HQR scores (2.34-2.48) found in the present study indicated that the handing qualities of the FTD were good/fair and that no or minimal compensation was required on behalf of the pilot to reach the desired performance. As such, pilots did not perceive any additional benefit of motion to the handling qualities of the FTD for the emergencies to which they were subject. Thus, pilot acceptance for the fixed-base condition can be conceived of as being equal to that of both the fullmotion and motion-cueing conditions. Self-reported workload assessments indicated no effect of motion configuration, but did reveal a significant effect of emergency type. Pilots judged the workload associated with the AFCS/ASE failure as significantly higher than that of the engine failure, but not the tail rotor failure. Closer examination revealed that much of this difference was attributable to higher workload rating associated with the motion cueing seat condition. It may have been that, given the nature of the AFCS/ASE emergency recovery (i.e., pilot induced



control oscillations), the full-motion provided a more realistic sense of motion than the motion-cueing seat and the fixed-base provided a stable platform, minimizing workload and disorientation. Interestingly, pilots showed preference for the motion-cueing conditions over the fixed-base condition for supporting recovery from the AFCS/ASE failure as evidenced by more favourable handling quality ratings, despite reporting higher workload. Finally, the results indicated that, compared to baseline pre-test (and post-lunch break), simulator sickness symptoms were significantly higher in the fullmotion condition. No between-configuration differences were significant. It is also important to note that most symptoms were relatively minor. Further, although one participant requested an unscheduled break, no participant experienced incapacitating symptoms of simulator sickness such that testing had to be terminated. The results of the present study suggest that fixedbase and motion cueing technologies are able to support flight training in the three in-flight rotary-wing emergencies to a comparable level to that of a fullmotion system. One possible reason for this finding is the high fidelity nature of the rest of the FTD (e.g., controls, visual, etc.). Many pilots reported that the FTD used in the present study was of a much higher fidelity than what they were used to in their regular training communities. As such, the general fidelity of the FTD may have satisfied their requirements, washing out any additional benefits the motion system may have offered. Alternatively, another possibility may be that motion and motion cueing technologies are not as important to rotary-wing emergency procedures training as may have been initially thought. Given the costs of purchasing, maintaining, and running high-fidelity full-motion simulators, the present study is of great importance to both military and industry. The comparable acceptance of pilots to the three motion conditions used in the present study may highlight an economical alternative (e.g. high-fidelity fixed-base system) to high-fidelity full-motion systems that are simply beyond the financial means of smaller scale training operations. Addressing the issue of pilot acceptance and workload in a training device is an important first step. Pilot acceptance of the training device is an important factor when considering the training potential of a simulator. As noted by McCauley (2006), pilots generally dislike no-motion. If the addition of high fidelity components can satisfy pilots and allow for acceptance of lower-cost fixed base trainers, it may be worth the cost, regardless of whether it benefits the actual transfer of skills to the aircraft. Future research should continue to examine objective flight performance data to investigate the ability of pilots to control the

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aircraft during such emergencies in various motion configurations. REFERENCES Burki-Cohen, J., Sparko, A. L., & Go, T. H. (2007). Training value of a fixed-base flight simulator with a dynamic seat. AIAA Modeling and Simulation Technologies Conference, 20-23 August 2007, AIAA-2007-6564. Burki-Cohen, J., Sparko, A. L., Jo, Y. J., & Go, T. H. (2009). Effects of visual, seat, and platform motion during flight simulator air transport pilot training and evaluation. Proceeding of the 15th International Symposium on Aviation Psychology, 27-30 April 2009. Cooper, G.E. and Harper. R.P. (1969). The Use of Pilot Rating in the Evaluation of Aircraft Handling Qualities. NASA TN D-5153. Hall, J. R. (1989). The need for platform motion in modern piloted flight training simulators (Technical Memorandum FM 35). Bedford, UK: Royal Aerospace Establishment, Minister of Defence. Hart, S. G. & Staveland, L. E. (1988). Development of NASA TLX (Task Load Index): Results of empirical and theoretical research. In: Human Mental Workload (P. A. Hancock and N. Meshkati (Eds.)), 139-183. North-Holland: Elsevier Science. Kennedy, R. S., Lane, K. E., Berbaum, K. S., Lilienthal, M. G. (1993). A Simulator Sickness Questionnaire (SSQ): A New Method for Quantifying Simulator Sickness, International Journal of Aviation Psychology, 3, 203-220. McCauley, M. E. (2006). Do helicopter training simulators need motion bases? United States Army Research Institute for the Behavioral and Social Sciences, Technical Report 1176, Arlington, VA. Sutton, D., Skelton, M., & Holt, L. S. (2010). Application and implementation of dynamic motion seats. Interservice/Industry Training, Simulation, and Education Conference (I/ITSEC). November, 2010.
