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Full-Text Articles in Engineering

Wave Propagation In A Randomly Inhomogeneous Medium - A Study Of The Problem, Kyle Hunter Dec 1991

Wave Propagation In A Randomly Inhomogeneous Medium - A Study Of The Problem, Kyle Hunter

Theses and Dissertations

The problem of calculating the scintillation index of an atmospherically propagating spherical wave is examined. The fourth statistical moment of the complex field is obtained by using Feynman (path) integral techniques applied to the stochastic parabolic equation. The general trajectory of each Feynman integral is approximated by a truncated Fourier-sine series and the infinite-fold integration of the Feynman integral is reduced to a three-fold Riemann integral which is shown to match results derived under different assumptions. This thesis is highly tutorial.

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Kalman Filter Tracking Of A Reflective Target Using Forward Looking Infrared And Doppler Return Measurements, Theodore D. Herrera Dec 1991

Kalman Filter Tracking Of A Reflective Target Using Forward Looking Infrared And Doppler Return Measurements, Theodore D. Herrera

Theses and Dissertations

Plume phenomenology experiments conducted in 1990 uncovered the existence of plume speckle reflectance emanating from the exhaust of a solid- propellant rocket motor due to the presence of metallic particulates in the plume. This impeded attempts, that are dependent upon the speckle return of an actively illuminated target hardbody, to discern the plume/hardbody interface. This thesis investigates the feasibility of employing the Doppler return phenomenon in discerning the plume/hardbody interface and locating the hardbody center-of-mass. The potential of the Doppler phenomenon's utilization lies in the fact that the Doppler return frequency spectra of the plume and the hardbody respectively possess …

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Infrared Target Recognition, Brian D. Singstock Dec 1991

Infrared Target Recognition, Brian D. Singstock

Theses and Dissertations

In this thesis, three approaches were used for Automatic Target Recognition (ATR). These approaches were shape, moment and Fourier generated features, Karhunen-Loeve transform (KLT) generated features and Discrete Cosine Transform (DCT) generated features. The KLT approach was modelled after the face recognition research by Suarez, AFIT, and Turk and Pentland, MIT. A KLT is taken of a reduced covariance matrix, composed all three classes of targets, and the resulting eigenimages are used to reconstruct the original images. The reconstruction coefficients for each original image are found by taking the dot product of the original image with each eigenimage. These reconstruction …

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Image Analysis Using Gabor Transforms: Correlated With Human Saccadic Movement Data To Identify The Human Visual Search Strategy, Ralph J. St John Dec 1991

Image Analysis Using Gabor Transforms: Correlated With Human Saccadic Movement Data To Identify The Human Visual Search Strategy, Ralph J. St John

Theses and Dissertations

This thesis investigated whether a relationship exists between the Gabor Correlation Coefficient (GCC) magnitudes of fixation points for a set of images viewed by six subjects and the human visual search strategy. A couple of different relationships were investigated. First, the data were analyzed to determine if the GCC magnitudes of human fixation points predicted the time ordered sequence of human fixation points during the performance of a visual search. Second, the data were analyzed to determine if there was a significant difference between the GCC magnitudes of the human fixation points and the GCC magnitudes of a random set …

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Optical Image Segmentation Using Wavelet Correlation, Steven D. Pinski Dec 1991

Optical Image Segmentation Using Wavelet Correlation, Steven D. Pinski

Theses and Dissertations

This research introduces an optical method of segmenting potential targets using wavelet analysis. Implementation of an optical Harr wavelet is fulfilled using a magneto-optic spatial light modulator (MOSLM). Two methods of controlling wavelet dilation are explored: (1) spatial filtering of a ternary modulated MOSLM; (2) a single aperture positioned in front of a binary modulated MOSLM. Segmentation is performed through Vander Lugt correlation of a binarized image with a binarized optical wavelet. Three different image binarization methods are investigated for use in the correlation scheme: (1) average pixel value over an entire scene; (2) localized 4 x 4 pixel average …

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An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki Dec 1991

An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki

Theses and Dissertations

Recurrent and feedforward artificial neural networks are developed as wavefront reconstructors. The recurrent neural network studied is the Hopfield neural network and the feedforward neural network studied is the single layer perceptron artificial neural network. The recurrent artificial neural network input features are the wavefront sensor slope outputs and neighboring actuator feedback commands. The feedforward artificial neural network input features are just the wavefront sensor slope outputs. Both artificial neural networks use their inputs to calculate deformable mirror actuator commands. The effects of training are examined.

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A Topographical Analysis Of The Human Electroencephalogram For Patterns In The Development Of Motion Sickness, George S. Vogen Dec 1991

A Topographical Analysis Of The Human Electroencephalogram For Patterns In The Development Of Motion Sickness, George S. Vogen

Theses and Dissertations

A topographical analysis was performed on 12 electroencephalograms (EEGs) collected from 10 volunteers who experienced motion sickness through cross-coupled Coriolis stimulation. Seven males and three females participated in the research conducted at the Air Force Institute of Technology, Wright- Patterson AFB. Two male volunteers participated in double-blind placebo/ phenytoin trials. Static brain maps and dynamic EEGs which focused on delta (below 3Hz) activity during the development of motion sickness revealed a seizure-like propagation pattern. With initial symptoms, a clear left parietal focus was seen in all records. A less dominant left fronto-temporal focus was present in 11 of the 12 …

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Analysis Of Orbital Elements And Atmospheric Activity To Ascertain Possible Presence Of An Ion Propulsion Capability Aboard Salyut 7/Cosmos 1686, Kris R. Howard Dec 1991

Analysis Of Orbital Elements And Atmospheric Activity To Ascertain Possible Presence Of An Ion Propulsion Capability Aboard Salyut 7/Cosmos 1686, Kris R. Howard

Theses and Dissertations

The purpose of this study was to analyze solar and geomagnetic activity in concert with orbital element data for the Soviet space station Salyut 7 as a means toward a determination of the possible use of an ion propulsion source aboard Salyut 7 and the Cosmos 1686 module to which it was docked. Solar activity was represented by sunspot number and 10.7-cm solar radio flux, and geomagnetic activity was represented by the general activity indices kp and Ap. The effects of atmospheric activity were examined both by direct comparison with orbital data, and by using solar and …

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An Expert System For The Civil Engineering In-Service Work Plan, Philip W. Melancon Dec 1991

An Expert System For The Civil Engineering In-Service Work Plan, Philip W. Melancon

Theses and Dissertations

Civil Engineering managers make many decisions each day which could be aided using expert system technology. One of the most important decision processes affecting CE operations is the scheduling of work order to be accomplished each month. A good work order schedule, or In-Service Work Plan (IWP), can ensure that material and manpower resources are fully utilized, that base facilities are properly maintained, and that customers are satisfied. The purpose of this research was to build and test a PC-based prototype expert system to schedule the IWP. Expanding on previous research, a multiplicative weighting technique was developed to provide relative …

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Thermomechanical Fatigue Of Scs-6/Β21-S [0/90]2s Composite, Dana G. Hanson Dec 1991

Thermomechanical Fatigue Of Scs-6/Β21-S [0/90]2s Composite, Dana G. Hanson

Theses and Dissertations

The objective of this study was to investigate the material behavior of SCS-6/β21-S [0/90]2s in a thermomechanical fatigue environment. Samples of the SCS-6/β21-S composite were subjected to in-phase and out-of-phase cyclic loading; four samples were tested under in-phase conditions and eight samples were tested under out-of-phase conditions. Stress, temperature, and total strain values were acquired during the test sequence and analyzed for indication of possible trends. Experimental results indicated in-phase specimen possessed shorter fatigue lives then their out-of-phase counterparts above the static first ply failure of the matrix. The out-of-phase specimen showed a shorter fatigue life below the first …

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Application Of Mixed H2/H∞ Optimization, John J. Kusnierek Nov 1991

Application Of Mixed H2/H∞ Optimization, John J. Kusnierek

Theses and Dissertations

A non-conservative optimization technique is utilized to examine the problem of minimizing the 2 norm of one transfer function subject to an ∞-norm bound on another transfer function. For single exogenous input/ single exogenous output systems this non conservative mixed solution is shown to be up to 5% better in a specific example. For single exogenous input/two exogenous output systems the mixed solution is shown to be up to 27% better than a previous technique for a specific example. Finally, a two exogenous input/two exogenous output practical system is examined to demonstrate the utility of this mixed optimization technique.

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Application Of Low Thrust Propulsion Techniques To Satellite Attitude Control Systems, Jeffrey J. Abbott Nov 1991

Application Of Low Thrust Propulsion Techniques To Satellite Attitude Control Systems, Jeffrey J. Abbott

Theses and Dissertations

Equation of motion for a satellite controlled through continuous, low thrust propulsion systems are analyzed through numerical integration techniques. The equations of motion are derived using the Euler Moment Equations. The properties of the satellite model are based upon the Intelsat VII design of communications satellite. A simple rate and error feedback controller is used in providing active attitude control about two and three axes. Perturbation models are created and applied based upon the satellite model. Parameters varied include thrust levels and controller deadband widths. System response times, pointing accuracy, and total impulse required for attitude control are determined as …

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Comparative Analysis Of Guidance Algorithms For The Hyper Velocity Missile And Afti/F-16, Edward G. Rice Nov 1991

Comparative Analysis Of Guidance Algorithms For The Hyper Velocity Missile And Afti/F-16, Edward G. Rice

Theses and Dissertations

This project has provided me with endless intrigue. In considering the problem of guiding a hyper-velocity missile from a moving platform to a moving target, a common perception said it was just another Kalman Filtration design challenge. I began with lofty intentions of running a full up extended Kalman filter simulation but I became enthralled with the limited work available on the physical limitations of basic guidance algorithms. This became the emphasis of this project. The best filter scheme cannot overcome a guidance algorithms physical limitation. Only with an understanding of these limitations can one effectively integrate a guidance scheme …

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Steady-State Production And Quenching Of Br(2P½), Ralph F. Tate Nov 1991

Steady-State Production And Quenching Of Br(2P½), Ralph F. Tate

Theses and Dissertations

The spin orbit relaxation of atoms has been investigated in a steady state infrared fluorescence experiment. A CW argon ion laser operating at 488 nm was used to photodissociate gas-phase Br into equal quantities of Bromine and Bromine atoms. The resulting 2.7 µm emission was observed as a function of added quenching gas. A steady-state analysis was used to determine quenching rates for SF6, N2, O2, He, Ne, Ar, Kr, and Xe, relative to quenching by the parent molecule. Limitations in the apparatus prevented determination of the quenching rate coefficient for Br2. …

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An Investigation Of Project Management Techniques For Scheduling Raaf Depot Level Maintenance, Kerry M. Bayley Sep 1991

An Investigation Of Project Management Techniques For Scheduling Raaf Depot Level Maintenance, Kerry M. Bayley

Theses and Dissertations

This research investigates scheduling performances of commercial project management software. It is based on difficulties that the Royal Australian Air Force experienced in evaluating microcomputer-based packages in maintenance task scheduling of aircraft undergoing Depot Level Maintenance. A literature review found only one paper quantifying commercial software performances. No standard performance metrics or test data were found. Several packages were evaluated using a common set of 110 single-project resource- constrained networks. The performance measure used was closeness to optimally minimum Total Durations. No package performed best on all problems. On average, the best produced schedules 5.2% longer than optimal, with 95 …

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An Analysis Of Fixed Wing Tactical Airlifter Characteristics Using An Intra-Theater Airlift Computer Model, Paul Pappas Sep 1991

An Analysis Of Fixed Wing Tactical Airlifter Characteristics Using An Intra-Theater Airlift Computer Model, Paul Pappas

Theses and Dissertations

This study used computer simulation to identify which tactical airlifter characteristics most significantly affected tactical airlift capability in a given scenario. The Generalized Air Mobility model was used to simulate a tactical airlift system. Aircraft characteristics within the model were grouped into six variables. A 2(6) two level full factorial experimental design was used to assess the effect of changes in aircraft characteristics on the effectiveness of the tactical airlift system. Yates algorithm was used to identify significant terms based upon the results of the factorial experiment. These significant terms were used to develop a parsimonious regression model that represented …

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Education Necessary For Air Force Software Managers To Use The Ada Programming Language And Software Engineering Effectively, James W. Worley Jr. Sep 1991

Education Necessary For Air Force Software Managers To Use The Ada Programming Language And Software Engineering Effectively, James W. Worley Jr.

Theses and Dissertations

This research investigated the perceived Ada and software engineering education needs of software managers throughout the Air Force and provided recommendations to Air Staff for developing the education. Since the Department of Defense mandated all DOD agencies use the Ada programming language for software development, the education of the personnel who have to support the policy has lagged behind the implementation Ada is not a simple language to use and is only fully effective if used with sound software engineering principles. A survey was given to Air Force mid-level personnel who manage software in some capacity. Of the software personnel …

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An Investigation Of The Air Force Risk Model, Thomas R. O'Hara Sep 1991

An Investigation Of The Air Force Risk Model, Thomas R. O'Hara

Theses and Dissertations

This study develops a dependent component cost risk model validation methodology and applies it to the Air Force Risk Model. The validation process consists of ensuring that logically consistent input parameters are acted on properly by the cost risk methodology. users of all dependent component risk models must be concerned with logically consistent input parameters. Two criteria define logical consistency. The first is the correlation matrix consistency and the second is the consistency between pairs of cost distributions. Three validation criteria are defined and used to validate a cost risk model. The first criterion is that the process must maintain …

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A Guide For The Consideration Of Composite Material Impacts On Airframe Costs, Jeffrey L. Isom Sep 1991

A Guide For The Consideration Of Composite Material Impacts On Airframe Costs, Jeffrey L. Isom

Theses and Dissertations

This study provides a guide to cost analysts who must consider the impact of composite materials on airframe costs. A literature review was conducted to determine the availability of cost models which incorporate the effect of composites on cost. A number of models are available, but no individual model was found that is applicable for every situation. In order to provide a baseline upon which analysts can compare model results as well as provide guidance in selecting cost drivers, a Delphi survey was conducted. Questionnaire results indicate that composite weight (as a percentage of total weight), composite part complexity, percentage …

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A Model For Estimating Aircraft Recoverable Spares Annual Costs, Phillip L. Redding Sep 1991

A Model For Estimating Aircraft Recoverable Spares Annual Costs, Phillip L. Redding

Theses and Dissertations

This thesis covers three objectives: (1) develop a background reference document concerning recoverable spares cost estimating; (2) evaluate a representative sample of existing spares cost models; and (3) use aircraft physical and performance characteristics to develop a model for estimating annual replenishment spares cost. A condemnations cost estimating relationship (CER) was developed first and then both a CER and spreadsheet generated factors which related condemnations to replenishment spares costs were developed. For the condemnations CER, only logarithmic transformations provided statistically acceptable results, and even these models exhibited wide prediction intervals due to large amount of variability in the CER databases …

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An Evaluation Of Logistics Support For F-16 Aircraft Owned By Foreign Countries, Paul J. Lyons Sep 1991

An Evaluation Of Logistics Support For F-16 Aircraft Owned By Foreign Countries, Paul J. Lyons

Theses and Dissertations

The purpose of this thesis was to examine the logistics support provided by the United States Air Force (USAF) for F-16 aircraft owned by foreign countries. The research drew from historical trends and personal experiences to examine the ability of the U.S. to provide logistics support for F-16 aircraft owned by U.S. allies. The study found that timely, efficient support of FMS customers possessing F-16 aircraft does not appear to be a principal concern of the USAF logistics system. Complexity of processes, untimely responses, and failure to consider customer needs are common failings on the part of the USAF.

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Study On In-Theater Maintenance Support For Poaf F-16, Rui J. Gomes Sep 1991

Study On In-Theater Maintenance Support For Poaf F-16, Rui J. Gomes

Theses and Dissertations

The purpose of this study was to evaluate the capacity to generate a desired level of sorties of the F-16 weapon system. This capacity depends on the maintenance concept and structure, that defines a specific level of in-theater resources available. The theater is intended to reflect Portuguese Air Force logistic operations planned for the F-16, with one operational base and a possible Centralized Intermediate Repair Facility (CIRF), not co-located. The TSAR simulation program and one USAF database was used to perform the evaluation were defined and compared. The study focused on the unscheduled maintenance tasks and repairable items, in particular …

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Challenges To United States Tactical Air Force Aircraft Maintenance Personnel: Past, Present And Future, Barbara L. Harris Sep 1991

Challenges To United States Tactical Air Force Aircraft Maintenance Personnel: Past, Present And Future, Barbara L. Harris

Theses and Dissertations

This study assessed the challenges Tactical Air Force (TAF) aircraft maintenance personnel face as a result of the TAF reorganization. The goal was to provide aircraft maintenance managers a basis for evaluating and meeting those challenges. To accomplish this, emphasis was placed on documenting the concepts, events, and conditions which led to changes in military aircraft maintenance from the birth of aviation to the present. Current issues such as the proposed move to two-level maintenance and the formation of the TAF composite and Objective Wings were also addressed. Research was conducted through the review of available historical documents, complemented by …

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Inaccurate Data Entry Into The Air Force Maintenance Data Collection System, Jon R. Determan Sep 1991

Inaccurate Data Entry Into The Air Force Maintenance Data Collection System, Jon R. Determan

Theses and Dissertations

This research investigated the data collection environment under the Core Automated Maintenance System (CAMS), a computerized information system used in the Air Force's aircraft maintenance complexes. The research measured maintenance personnel's perception of the nature, extent, and causes of data inaccuracies occurring in the CAMS data collection environment. The nature was differentiated as being either intentional or accidental. Maintenance personnel felt that difficulty in entering information into CAMS accounted for the largest percentage of intentional errors and that insufficient training on CAMS accounted for the largest percentage of accidental errors. A comparison of this research to the results of earlier …

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An Evaluation Of The Implementation Of Two-Levels Of Maintenance At Strategic Air Command Intercontinental Ballistic Missile Bases, Alan H. Russell Sep 1991

An Evaluation Of The Implementation Of Two-Levels Of Maintenance At Strategic Air Command Intercontinental Ballistic Missile Bases, Alan H. Russell

Theses and Dissertations

As a result of the 1979 Defense Management Review, Headquarters, Strategic Air Command has initiated programs of alternative levels of maintenance in order to trim excess costs. This study investigates the suitability of the SAC program which changed selected base-level strategic missile maintenance tasks from three to two-levels of maintenance. Using an opinion oriented questionnaire, this research surveyed a sample of missile maintenance personnel on their perceptions of the SAC program which implemented an alternative to intermediate-level maintenance. Analysis of survey results show respondents tended to believe the SAC program has not added benefit to their mission effectiveness. Other studies …

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An Exploratory Application Of Neural Networks To The Sortie Generation Forecasting Problem, James M. Dagg Sep 1991

An Exploratory Application Of Neural Networks To The Sortie Generation Forecasting Problem, James M. Dagg

Theses and Dissertations

This exploratory study assesses the accuracy of backpropagation neural networks in predicting sortie generations, given pre-specified levels of air base resources. Single hidden layer networks and two-way interaction regression metamodels were fitted to simulated data previously generated by way of a factional design for ten factors at two levels, and subsequently tested (cross-validated) via an independent testing sample. It was determined that regression metamodels were generally superior in predicting unseen cases, while their network counterparts exhibited far better goodness-of-fit characteristics. The research consistently emphasizes that goodness-of-fit in no way necessarily implies goodness-of-prediction, in that different non-equivalent statistical measures are required …

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Development Of An Operationally-Oriented Measure Of Sustainability, Moira D. Williams Sep 1991

Development Of An Operationally-Oriented Measure Of Sustainability, Moira D. Williams

Theses and Dissertations

This thesis proposes a framework for evaluating sustainability in the Air Force and for determining an appropriate measure of effectiveness that is both meaningful in a military sense and useful in planning and programming decisions. Following a literature review of organizational performance measures and strategy formulation, Michael Porter's Competitive Analysis model for strategy selection was presented. This model was then used to evaluate case studies in which organizations faced strategic decisions and to suggest measures by which these organizations could determine their effectiveness. The model was then shown to be applicable to the Air Force, and recommendations on implementing such …

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Desert Express: An Analysis On Improved Customer Service, Thomas C. Thalheim Sep 1991

Desert Express: An Analysis On Improved Customer Service, Thomas C. Thalheim

Theses and Dissertations

Operation Desert Shield/Storm provided an opportunity to test the planning for U.S. forces to operate in a low intensity conflict. Both operations provided the opportunity for the logistics community to observe how the support forces provided the required supplies to the forward combat forces. In response to customers' requests, the U.S. Transportation Command created Desert Express, a daily package express flight from Charleston, SC to Saudi Arabia. The research question addresses the how and why Desert Express came about. Additional investigative questions cover the following: mission objectives, planners' and customers' expectations, system performance, and implications on the Defense Transportation System. …

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A Comparison Of The Air Force, Army, And Navy Test And Evaluation Reliability And Maintainability Data Base Systems, Donald L. Scantlan Jr. Sep 1991

A Comparison Of The Air Force, Army, And Navy Test And Evaluation Reliability And Maintainability Data Base Systems, Donald L. Scantlan Jr.

Theses and Dissertations

This study was conducted to create a single source document which could be used by test and evaluation personnel involved in joint programs for translating reliability and maintainability terms. The comparison begins by describing the forms, data elements, and data items, as collected by the Air Force's System Effectiveness Data System, the Army's Reliability, Availability, Maintainability Logistics System, and the Navy's Maintenance and Material Management, Maintenance Data System. The Findings paragraph is a stand-alone document which could serve as a translating dictionary for reliability and maintainability data elements between the different service's data systems. Upon the conclusion of this study, …

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A Study Of Pilot Attitudes Regarding The Impact On Mission Effectiveness Of Using New Cockpit Automation Technologies To Replace The Navigator/Weapon System Officer/Electronic Warfare Officer, William K. Starr, Donald A. Welch Sep 1991

A Study Of Pilot Attitudes Regarding The Impact On Mission Effectiveness Of Using New Cockpit Automation Technologies To Replace The Navigator/Weapon System Officer/Electronic Warfare Officer, William K. Starr, Donald A. Welch

Theses and Dissertations

This study analyzed the self-reported survey responses of 404 Air Force pilots concerning their perceptions of using advanced cockpit technologies to replace the Navigator, Weapon System Officer, and Electronic Warfare Officer (Nav/WSO/EWO) and the impact of advanced cockpit technologies on combat mission effectiveness. The first objective of this study was to compare, by aircraft type, the mission effectiveness factors that are always critical and almost always critical to the success of a combat mission. The second objective was to examine, from the pilot's point of view, the Nav/WSO/EWO's contribution (NAVCRIT) to enhancing the combat mission effectiveness factors. The third objective …

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