USAARL Report No. 89-20 Simulator Sickness in the AH-IS (Cobra) Flight Simulator BY Daniel W. Gower, Jr. Biodynamics Research Division and Jennifer Fowlkes Essex Corporation Orlando, Florida September 1989 Approved for public release; dlstrlbution unllmlted. United States Army Aeromedical Research Laboratory Fort Rucker, Alabama 36362-5292 Notice Qualified m Qualified requesters may obtain copies from the Defense Technical Information Center (DTEC), Cameron Station, Alexandria, Virginia 22314. Orders will be expedited if placed through the librarian or other person designated to request documents from DTIC. Change af address Organizations receiving reports from the U.S. Army Aeromedical Re- search Laboratory on automatic mailing lists should confirm correct address when corresponding about laboratory reports. Disposition Destroy this report when it is no longer needed, Do not return it to the originator, Disclaimer The views, opinions, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other official documentation. Citation of trade- names in this report does not constitute an official Department of the Army endorsement or approval of the use of such commercial items. Human use -~ Human subjects participated in these studies after giving their free and informed voluntary consent. Investigators adhered to AR 70-25 and USAMRDCR eg 70-25 on Use of Volunteers in Research. Reviewed: LTC, MS Director, Biodynamics Division COL, MS Chairman, Scientific Commanding Review Committee UN-IF1 D SECURITYC Liii Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 la. REPORT SECURITY CLASSIFICATION 1 b. RESTRICTIVE MARKINGS UNCLASSIFIED 2a. SECURITY CLASSIFICATION AUTHORITY 3 DISTRIBUTION /AVAILABILITY OF REPORT DeDutv Commander for Science Public release; distribution unlimited 2b. DECLASSIFICATION/DOWNGRADING SCHEDULE 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S) OSAARL Report No. 89-20 6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION U.S. Army Aeromedical Research (/f applicable) U.S. Army Medical Research and Development Laboratory SGRD-UAD Command 6c ADDRESS (City, State, and ZIPCode) 7b. ADDRESS (City, State, and ZIPCode) Fort Detrick Fort Rucker, AL 36362-5292 Frederick, MD 21701-5012 Ea.N AME OF FUNDING /SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable) 3c ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNIT ELEMENT NO. NO. NO. ACCESSION NO. 62777A 331627776879 165 Il. TITLE (Include Security Clauification) (U) Simulator Sickness in the AH-1S (Cobra) Flight Simulator It. PERSONAL AUTHOR(S) Daniel W. Gower, Jr., and Jennifer Fowlkes 13a.T YPE OF REPORT 13b. TIME COVERED Final 1989, September 16. SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessarya nd identify by block number) Simulator sickness, training, motion sickness, adaptation, FIELD GROUP SUB-GROUP l& n7 equilibrium, ataxia 06 10 19.. ABSTRACT (Continue on reverse if necessarya nd identify by block number) me U.S. Army Aeromedical Research Laboratory conducted field studies of operational flight simulators to assess the incidence and severity of simulator sickness. Simulator sickness here refers to the constellation of motion sickness related symptoms that occur in simulator due to visual representation, motion base representation, or combination of the two represen tations of flight. The incidence rates and relative frequency of specific symptoms are presented. Correlational factors such as recent simulator experience, current state of health, overall flight experience, mission scenario, and flight dynamics are presented. Thi report ranks the Army's flight simulators in comparison to the 10 Navy simulators studied by the Naval Training Systems Center, Orlando, FL. The study further reinforces the need for studies to understand perceptual rearrangement, adaptation/readaptation, and pilot suscepti- bility to the effects of simulation. Design criteria for simulators, as well as those train ing guidelines necessary to cope with this phenomenon also must be addressed. 20. DISTRIBUTION /AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION UNCLASSIFIED ~UNCLASSIFIEDIUNLIMITED Cl SAME AS RPT. 0 DTIC USERS Za. NAME OF RESPONSIBLE INDIVIDUAL 22b. TELEPHONE (/n&de Area Code) 22~. OFFICE SYMBOL Chief, Scientific Information Center (205) 255-6907 SGRD-UAX-SI DD Form 1473, JUN 86 Previouse ditionsa re obsolete. ATION OF THIS PAGE Table of contents Page List of figures ............................................. 2 List of tables .............................................. 3 5 Introduction ................................................ ........... 5 U.S. Army's involvement with simulator sickness The nature of simulator sickness .......................... 6 ................................................... 8 Materials Description of the aircraft system ........................ 8 Description of the simulation system ...................... 17 29 Method ...................................................... 29 Aviators ................................................... 29 Measures .................................................. 31 Procedure ................................................. 32 Results ..................................................... Symptomatology ............................................ 32 Postural stability ........................................ 38 38 Correlations .............................................. Pilot variables ........................................... 39 Simulator variables ....................................... 40 Training variables ........................................ 41 Symptomatology by mission and seat .......................... 42 42 Mission ................................................... Seat ...................................................... 43 45 Discussion .................................................. 46 Recommendations ............................................. 48 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix A. Simulator sickness survey.................,..... 52 Appendix B. Variable descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . 63 1 List of tables Table Page 1. Basic, advanced, and instrument maneuvers, and emergency procedures that can be performed in the simulator . . . . . . . . . ..*......*............*.... 20 2. Percentage (frequencies) of aircrews reporting postflight symptomatology in the AH-1S FWS simulator . . . . ..*.........*.......................... 33 3. Percentage of pilots reporting key symptomatology in seven helicopter simulators...................... 34 4. Pre- and post-SSQ means (standard deviations) and paired t-test values............................. 35 5. Means, standard deviations, minimum/maximum scores, t-test values, and observations for pre- and post-WOFLEC, SONLEC, and SOPLEC measures............ 38 6. Intercorrelations among variables..................... 39 7. Frequencies for variable lldiscomfort hampers training" . ..**.......*..*...*.*~.~...0.*.*.~ 41 8. Mean (standard deviations) SSQ scores by mission...... 42 9. Scenario content data (means and standard deviations) for different missions flown in the AH-1s simulator . . . . . . . . . . . ..*..............**... 42 10. SSQ scores by seat . . ..*..............*................ 43 11. Mission and scenario content data for copilot amd copilots . . . . . ..*............................... 44 l 2 List of fisures Page Figure 1. Principal dimensions .................................. 9 2. Authorized armament configuration ..................... 10 3. Universal turret components ........................... 11 4. TOW missile launcher .................................. 12 5. Wing gun pod .......................................... 13 6. Folding fin aerial rocket (2.75-inch) launcher ........ 14 . 16 7. Helmet sight subsystem (HSS) .......................... a. Typical simulator and computer rooms of system complex ............................................. 18 9. Instructor/operator station general layout ............ 21 10. Typical visual display system installation ............ 23 25 11. COllimating optics representation ..................... 12. Ocular convergence representation ..................... 25 13. Basic collimation concept ............................. 27 14. Mirror/beamsplitter optical diagram ................... 28 15. SSQ visuomotor subscale ............................... 36 16. SSQ nausea subscale ................................... 36 17. SSQ disorientation subscale ........................... 37 18. SSQ total severity score .............................. 37 3 ____________________-________-_--_--_-------------------------------------------------------------------__________ __ This page intentionally Left blank. _________________----------_----_-----------------------------------------------------------------_--______________ _ 4 Introduction U.S. Army's involvement with simulator sickness Prior to the actual fielding of the AU-64 Apache combat mission simulator (CMS) at U.S. Army installations, training of Apache pilots was conducted at the Singer Link facility in Binghamton, New York. Anecdotal information indicated some of the pilots and instructor operators (IO) were experiencing symptoms of simulator sickness resembling those reported in U.S. Navy and U.S. Coast Guard systems. Some students took Dramamine'" to alleviate their symptoms. In May 1986, documentation of the problem reached the U.S. Army Aeromedical Research Laboratory (USAARL) at Fort Rucker, Alabama. In July 1986, the Aviation Training Brigade at Fort Rucker formed a study group to examine the Apache training program. One of the issues studied was simulator sickness. A survey of existing training records and a literature search were conducted by USAARL in August 1986. Training records of 115 students from the CMS showed that 7 percent of the students had sufficient symptoms to warrant a comment on their grade slips. The literature search led USAARL investigators to visit the Naval Training Systems Center (NTSC) in Orlando, Florida. From that association has grown a working relationship geared to capitalize on lessons learned from past research and expand the database of simulator sickness studies. As part of that search, it also was discovered that a U.S. Army flight surgeon had conducted an independent survey of the incidence of simulator sickness in the AH-l Cobra flight weapons simulator (FWS) located in Germany (Crowley, 1987). In the report to the Army study group, it was recommended a problem definition study be conducted to ascertain more accurate- ly the scope and nature of.the problem of simulator sickness in the Apache CMS. The request for that study was received from the Directorate of Training and Doctrine, Fort Rucker, Alabama, in February 1987. The protocol for the study was approved by the USAARL Scientific Review Committee on 4 May 1987. USAARL Report No. 88-1 documents the results of that first study. As reported in Baltzley et al. (1989), 25 percent of those reporting aftereffects indicated their symptoms persisted longer than 4 hours while 8 percent lasted 6 hours or longer. The Army data presented in that report was contaminated with effects experienced by Apache pilots who had previous experience with the Cobra FWS. Problems with other Army simulator systems also have been documented since the first study. Most notable, aviators training in the new AH-l Cobra simulator were complaining of postsimulator exposure aftereffects which outlasted the training 5 period by several hours. The need for further studies was apparent. In September 1988 ,.USAARL received a request from the Direc- torate of Training and Doctrine at the U.S. Army Aviation Center at Fort Rucker, Alabama, requesting further field studies to assess the incidence of simulator sickness in the remaining visually-coupled flight simulators. The protocol was approved 19 October 1988 and collection of data began in January 1989. This report documents the results of the data collected at the AH-1s simulator site at Fort Rucker, Alabama. The nature of simulator sickness Simulator sickness is considered to be a form of motion sickness. Motion sickness is a general term for the constella- tion of symptoms which result from exposure to motion or certain aspects of a moving environment (Casali, 1986), although changing visual motions (Crampton and Young, 1953; Teixeira and Lackner, 1979) may induce the malady. Pathognomonic signs are vomiting and retching; overt signs are pallor, sweating, and salivation; symptoms are drowsiness and nausea (Kennedy and Frank, 1986). Postural changes occur during and after exposure. Other signs (Colehour and Graybiel, 1966; McClure and Fregly, 1972; Money, 1970: Stern et al., 1987) include changes in cardiovascular, respiratory, gastrointestinal, biomedical, and temperature regulation functions. Other symptoms include general discomfort, apathy, dejection, headache, stomach awareness, disorientation, lack of appetite, desire for fresh air, weakness, fatigue, confusion, and incapacitation. Other behavioral manifestations influencing operational efficiency include carelessness and incoordination, particularly in manual control. Differences between the symptoms of simulator sickness and more common forms of motion sickness are that in simulator sickness visual symptoms tend to predominate and vomiting is rare. Advancing engineering technologies permit a range of capabil- ities to simulate the real world through very compelling kinemat- ics and computer-generated visual scenes. Aviators demand realistic simulators. However, this synthetic environment can, on occasion, be so compelling that conflict is established between visual and vestibular information specifying orientation (Kennedy, 19753 Oman, 1980; Reason and Brand, 1975). It has been hypothesized that in simulators, this discrepancy occasions discomfort, or tfsimulator sicknessI as it has been labeled, and the cue conflict theory has been offered as a working model for the phenomenon (Kennedy, Berbaum, and Frank, 1984). In brief, the model postulates the referencing of motion information signaled by the retina, vestibular apparatus, or sources of somatosensory information to Vtexpectedlt values based on a neural 6 store which reflects past experience. A conflict between ex- pected and experienced flight dynamics of sufficient magnitude can exceed a pilot's ability to adapt, inducing in some cases simulator sickness. The U.S. Navy conducted a survey of simulator sickness in 10 flight trainers where motion sickness experience questionnaires and performance tests were administered to pilots before and after spme 1200 separate exposures (Kennedy et al., 1987b). From these measures on pilots, several findings emerged: (a) Specific histories of motion sickness were predictive of simulator sick- ness symptomatology; (b) postural equilibrium was degraded after flights in some simulators: (c) self-reports of motion sickness symptomatology. revealed three major symptom clusters: Gastroin- testinal, visual, and vestibular; (d) certain pilot experiences in simulators and aircraft were related to severity of symptoms experienced: (e) simulator sickness incidence varied from 10 to 60 percent: (f) substantial perceptual adaptation occurs over a series of flights; and (g) there was almost no vomiting or retching, but some severe nausea and drowsiness. Another recent study suggests that inertial energy spectra in moving base simulators may contribute to simulator sickness (Allgood et al., 1987). The results showed the incidence of sickness was greater in a simulator with energy spectra in the region described as nauseogenic by the 1981 Military Standard 1472C (MIL-STD-1472C) and high sickness rates were experienced as a function of time exceeding these very low frequency (VLF) limits. Therefore, the U.S. Navy has recommended, for any moving-base simulator which is reported to have high incidences of sickness, frequency times acceleration recordings of pilot/ simulator interactions should be made and compared with VLF guidelines from MIL-STD-1472C. However, in those cases where illness has occurred in a fixed-base simulator, other explana- tions and fixes are being sought. Of particular concern in the area of safety are simulator induced posteffects. Gower et al. (1987) showed that as symptoms decreased over flights for pilots training in the AH-64 CMS, suggesting that pilots were adapting to the discordant cues in the simulator, postflight ataxia increased suggesting that pilots were having to readapt to the normal environment. Such readapta- tion phenomena parallel findings from other motion environments including long-term exposure onboard ships (Fregly and Graybiel, 1965), centrifuges (Fregly and Kennedy, 1965) and space flight (Homick and Reschke, 1977). For example, Graybiel and Lackner (1983) found 54 percent of the posteffects of parabolic flight lasted longer than 6 hours and 14 percent lasted 12 hours or more. In their report, the primary symptoms reported were dizziness and postural disequilibrium. The similarity of 7