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Johnson, Walter A.
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HUD Symbology for Surface Operations: Command Guidance vs. Situation Guidance Formats

Monterey Technologies, Inc.-Becky L. Hooey
NASA Ames Research Center-David C. Foyle
Published 2002-11-05 by SAE International in United States
This study investigated pilots' taxi performance, situation awareness and workload while taxiing with three different head-up display (HUD) symbology formats: Command-guidance, Situation-guidance and Hybrid. Command-guidance symbology provided the pilot with required control inputs to maintain centerline position; Situation-guidance symbology provided conformal, scene-linked navigation information; while the Hybrid symbology combined elements of both symbologies. Taxi speed, centerline tracking accuracy, workload and situation awareness were assessed. Taxi speed, centerline accuracy, and situation awareness were highest and workload lowest with Situation-guidance and Hybrid symbologies. These results are thought to be due to cognitive tunneling induced by the Command-guidance symbology. The conformal route information of the Situation-guidance and Hybrid HUD formats provided a common reference with the environment, which may have supported better distribution of attention.
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A Simulator Solution for the Parachute Canopy Control and Guidance Training Problem

Systems Technology, Inc.-Jeffrey R. Hogue, Walter A. Johnson, R. Wade Allen
Published 1992-04-01 by SAE International in United States
Maneuverable round and ramair parachutes are flown by professional forestry firefighters, search and rescue personnel, and military combat teams when deployment by fixed or rotary aircraft is inappropriate. Parachute flight training requires the development of perceptual skills in canopy control, guidance, and energy management. These parachutists must learn to accurately sense motion visual cues, and predict and manage their trajectory. Parachute guidance and control can only be acquired through repeated practice. Canopy control training has been traditionally limited to a classroom lecture topic. There was no opportunity for the immediate student/instructor dialogue available during the extensive dual flight training used for conventional aircraft, where instruction can occur during the numerous practice landings available via rapid touch-and-go techniques.This paper describes a low-cost simulator which is specifically optimized to teach and allow practice of professional parachuting skills. The simulator allows an instructor to coach and instruct while a trainee maneuvers on a simulated parachute descent. Trainees can learn good parachute handling techniques and learn the consequences of poor techniques in complete safety. Simulated jumps can teach and…
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A Downhill Grade Severity Rating System

Systems Technology, Inc. Hawthorne, CA-Walter A. Johnson, Thomas T. Myers, Richard J. DiMarco, R. Wade Allen
Published 1981-11-01 by SAE International in United States
A Grade Severity Rating System (GSRS) was developed as a means for reducing the incidence and severity of truck accidents on downgrades. The ultimate result is a roadside sign at the top of each hill. The sign is tailored to the individual hill and gives a recommended maximum speed (to be held constant for the entire grade descent) for each of several truck weight ranges. This concept represents a major step forward in terms of grade descent safety because it tells the driver what to do directly, rather than giving him information which still requires evaluation under different loading conditions.
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Comprehensive Measurement of Ride of In-Service Trucks

Systems Technology, Inc., Hawthorne, CA-Henry R. Jex, John W. Zellner, Walter A. Johnson, Richard H. Klein
Published 1981-02-01 by SAE International in United States
This paper summarizes a comprehensive research program of the ride qualities of long-haul trucks. Factors are identified which contribute significantly to differences in ride quality between various truck models and configurations over a range of actual operating conditions. Detailed measurements of six floor and seat accelerations and driver and passenger ride ratings were made on ten in-service trucks over five segments, ranging from “smooth” to “rough,” of a typical California freeway. The experimental methodology is reviewed and validated, and example data and preliminary comparisons between the objective and subjective measures are presented.
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Vehicle Controllability in a Pavement/Shoulder Edge Climb Maneuver

Systems Technology, Inc. Hawthorne, CA-Richard H. Klein, Walter A. Johnson
Published 1978-02-01 by SAE International in United States
This paper describes the results of a test program to evaluate various roadway disturbances present in the driving environment. The specific objectives were to pare down the list of possible roadway disturbances to the worst cases, identify handling problem areas, find meaningful response parameters and compare responses of different vehicles which might influence the results.The program provided an accident data analysis, survey questionnaire results and full scale test results which found the pavement/shoulder dropoff (requiring an edge climb maneuver) to be the most severe and most likely disturbance to result in lane exceedance. This occurs when the vehicle is scrubbing one set of tires on the shoulder edge (or encountering the edge at too shallow an angle for climb), thereby climb), thereby requiring the driver to apply a large steering deflection to get the car to climb back onto the pavement. In this case the vehicle will “spin out” if the speed is high enough.Road tests were performed with four passenger cars in an attempt to obtain objective vehicle response performance measures as a function…
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The Effect on Drive Axles

Transmission & Axle Div., Rockwell-Standard Corp.-Walter A. Johnson
Published 1964-01-01 by SAE International in United States
The author discusses the use of retarders and their effects on drive axles, wheel bearing, and drive unit bearings under varying driving conditions and speeds. It appears the use of retarders for vehicle control during downhill operation has little effect on wheel bearing life but it does have a substantial effect on the drive unit bearing life. As long as conditions leading to surface destruction are avoided, the life of the drive gears is not likely to be affected by the use of retarders.
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