Among the many occupational hazards to which Army rotary-wing aviators are exposed is intense noise generated from the aircraft. The potential for permanent hearing loss and difficulty communicating in helicopter noise is well known; an appropriate way to evaluate a hearing-impaired pilot's safety risk due to hearing loss is not as well known. Previous research has studied communication ability in helicopter cockpit noise under different headsets, but there are not conclusive data on the combined effects of degraded speech intelligibility due to noise and flight workload under the headset technology currently available to Army helicopter pilots. In particular, there is a scarcity of information on pilots with hearing loss. Currently, Army Aeromedical standards stipulate audiometric threshold criteria for rated helicopter pilots to ensure their safe flying. If the standard is not met, a flight waiver for hearing is generally granted if the pilot demonstrates good (at least 84%) binaural word recognition ability in a quiet environment. A research study was conducted to evaluate Army helicopter pilot performance with regard to flight workload, communication signal quality, headset configuration, and pilot hearing ability. Objectives of the study included the ability to refine current Army audiometric hearing waiver criteria, and to yield data on which to base flight and headset selection recommendations for pilots. In general, it was believed that flight performance and ratings of situation awareness (SA) would decrease as flight workload increased and communication signal quality decreased, and that assistive communication devices coupled with headsets would afford improved flight performance over their passive counterpart. It was also hypothesized that normal-hearing pilots would perform better than hearing-impaired pilots would. Twenty Army helicopter pilots (one group of 10 pilots without a hearing waiver and one group of 10 pilots with a hearing waiver) participated in this study. The pilots flew three flights in a Black Hawk flight simulator, each with a different headset configuration and with varying flight workload levels and varying air traffic control (ATC) communication signal quality. Objective flight performance parameters of heading, altitude, and airspeed deviation and ATC command readbacks were measured. Additionally, measurements were taken on subjective measures of workload, SA, and headset comfort/speech intelligibility. Experimental results partially supported the research hypotheses. Results indicated that flight performance and ratings of SA were negatively affected by increased flight workload and decreased communication signal quality for both groups of pilots. Results also showed that a passive headset/passive earplug combination use by the hearing-impaired group of pilots led to degradation of certain flight performance parameters and lower ratings of SA than the headsets equipped with assistive communication technology; however, the same headset effect was not seen with the group of normal-hearing pilots. This study yielded results that support a conclusion that factors other than hearing thresholds and word recognition ability in a quiet environment should be considered when evaluating Army helicopter pilots flight safety with regard to hearing sensitivity. Rather, the synergistic effects of flight workload and communication signal quality with individual hearing levels should be considered when making continued flight recommendations and headset choice recommendations. Results also support a recommendation requiring hearing-impaired pilots to use assistive communication technology and not be permitted to fly with passive headset devices. Further research should include a functional hearing assessment in which pilot hearing requirements are determined and individual hearing abilities are compared to the requirements. / Ph. D.

This research examined human-machine performance in a General Aviation (GA) environment under dynamic conditions using a combination of field study and laboratory experimentation. Using this combination of methods, the functional system of pilots performing a landing approach (both instrument and visual) with a Cessna 172 to the Roanoke Regional Airport (ROA) was described and analyzed. In the field study, data collection was guided by an integrative method based on macroergonomics (ME) and distributed cognition (DC), allowing the cognitive aspects of a sociotechnical system to be treated as equally important as the organizational components. Also of interest was how pilot performance was affected by the introduction of nighttime and deteriorating weather conditions to this GA environment. Few statistically significant differences were found between pilots who flew by visual flight rules (VFR) and those who flew by instrument flight rules (IFR) or within each of these pilot groups in terms of objective flight performance. However, there were several significant differences between VFR and IFR pilots and within each pilot group in terms of workload and especially situation awareness across conditions; situation awareness for VFR pilots was found to be significantly reduced compared to situation awareness for IFR pilots in nighttime and deteriorating weather conditions (p < 0.05). In addition to these statistical findings and the methodological contribution of a joint systems/cognitive method, contributions of this dissertation include a greater understanding of the GA pilot/cockpit system and a systems-oriented cognitive model of this aviation environment as described by the ME/DC method for both VFR and IFR pilots. Further, procedural comparisons were performed between the flight simulator and the actual Cessna 172 used in the field study to increase our understanding of how to improve the validity associated with using simulators in research. Findings from both the laboratory and field studies in this research support new designs and technologies envisioned for future aviation systems that would assist the pilot during a landing approach such as weather information systems, head-up displays, synthetic vision, three-dimensional auditory displays, increased automation, and communications filters. Potential future applications of this research are also explored. / Ph. D.

This study was based on a portion of data collected in the first half of a proposed two-part survey examining the effects of unstable airline working conditions on pilots and their families. The survey was a descriptive, exploratory investigation of two pilot groups (n = 425). Data were drawn from a random sample of those pilots (n = 205) employed by an airline with chronic unstable working conditions, and those pilots (n = 220) employed by airlines with stable conditions. Several major variables from a multi-dimensional systems model of stress were selected to evaluate differences in stress symptoms, life event strains, family resources, and perceptions of control between pilot groups and between spouse groups. A major hypothesis tested by this report was that increases in pilot stress symptomology would be related to unstable airline working conditions. When differences between pilot groups and spouse groups were analyzed on the Family Inventory of Life Events (FILE), a self report symptoms of stress scale (SOS), the Family Adaptability and Cohesion Evaluation Scales (FACES III), and the Attribution Questionnaire, pilots and spouses found to have the highest stress symptoms and total family strains were those from the unstable airline. In addition, a large subtotal of pilot families across carriers were found to be low functioning families. The results of the study document the importance of unstable airline working conditions as an explanatory variable in examining pilot stress. It is suggested that understanding the pilot stress process depends on the recognition of work/family/individual systems interdependence. Implications of findings and directions for future research were presented. / M.S.

This thesis investigates two main aspects of air transportation system, demand and capacity. The first study aims to estimate the potential market for Zip Vehicles, an advanced commuter type of aircraft equipped with automation and electric propulsion technologies. A Multinomial Logit Model was developed to estimate the mode choice behavior of commuters between Zip vehicle, auto and transit in seven metropolitan areas in the United States. The results showed that the Out-of-Vehicle travel time plays an important role in the decision process of commuters. Zip Vehicle is predicted to achieve residual demand with the current technologies and could become more competitive if it was equipped with Vertical Take-Off Technology. The second study developed a hybrid airport runway capacity model that blends both deterministic and simulation techniques. The model includes a graphic user interface that allows high degree of freedom to modify input parameters, such as airport information, weather conditions, minimum separation distances and aircraft grouping system. The model is widely validated and it appears to be a consistent solution for estimating airport capacity at different levels and with various degree of extensibility. / Master of Science

No / All forms of corneal refractive surgery can sometimes cause an increase in optical aberrations and scattered light, which can affect visual performance. The purpose of this study was to develop a suitable test that was sensitive to retinal image degradation in subjects who have undergone excimer laser refractive surgery and that was also relevant to visual demands in commercial aviation. Methods: Assessment of the visual environment and the tasks involved in piloting a commercial aircraft formed the basis for the selection of the test parameters. The new contrast acuity assessment (CAA) test covers a functional visual field of ±5° and is based on minimum spatial vision requirements for commercial pilots. Results: Data measured in 100 normal subjects were used to define the `standard normal observer' and the range of variation for the parameters of the test. This approach makes it possible to quickly establish whether a given subject's performance falls within the range of the standard normal observer. The test is also administered under low ambient illumination since flying at night involves mesopic levels of light adaptation when the pupil size is large and the effects of aberrations and scattered light are therefore more pronounced. Conclusion: The results of the test are simple to interpret and reveal visual performance that falls outside the normal range as a result of either significant degradation of retinal image quality (caused by increased aberrations and scattered light) or abnormal processing of visual information in the retina and/or the visual pathway.

Communication systems have an important role to play in managing the safe and efficient operation of the National Airspace System (NAS). The users of the NAS, from the commercial transport aircraft to hobby airplanes can all benefit from the recent advances in digital communication technology especially as the capacity of the analog voice systems is surpassed by the growth in air traffic. One of the benefits of the new digital data links being developed is to allow delivery of real time weather information to the cockpit of aircrafts. Weather information is essential to flight operations and until recently there were only limited voice and text weather reports available to the pilot. With data links, graphical weather in the cockpit is possible and also highly desired by the aviation community. This thesis will develop a decision model and analysis tool for product developers of weather information systems that need to select appropriate data link technology for which to develop their weather information systems. A comparative analysis of the aeronautical communications systems is done with the view of satisfying end-user requirements for weather information and achieving market success. A study of the various data links is conducted to gain an understanding of their performance characteristics and implementation issues. A consumer survey was designed and valuable insight into the requirements and opinions of pilots was gained. The method of Quality Function Deployment (QFD) was employed to find the most important technical characteristics of the data links to satisfy the consumer requirements captured in the survey. The decision model consisting of the QFD and also further technical assessment was implemented in software to allow any scenario of product requirements and data link to be performed. / Master of Science

Les textes dénommés, par commodité, annexes à la convention relatives à l'aviation civile internationale, dite Convention de Chicago, ne sont pas, au regard du droit international des annexes à ladite convention car elles n'ont pas la même valeur juridique que celle-ci. Elles n'acquièrent force juridique qu'une fois transposées dans le droit interne des Etats qui peuvent d'ailleurs y déroger. Pendant des années, la non transposition des annexes dans le droit positif des Etats a été tolérée. Cependant, depuis l'instauration du système des audits de sécurité et de sûreté, l'absence de transposition peut entrainer le placement des Etats sur le site sécurisé de l'organisation de l'aviation civile internationale (oaci) et/ou sur la liste noire de l'Union Européenne. Par ces deux faits, les annexes ont acquis une évolution ayant des conséquences significatives la majorité des Etats, notamment africains, où le taux de non conformité aux annexes est le plus élevé de tous les continents ; ce qui ne va sans conséquence pour les relations aériennes internationales et pour le développement de l'industrie de l'aviation civile pour le continent africain / The texts referred to, for convenience, annexes to the Convention on International Civil Aviation, known as the Chicago Convention, are not, under international law annexes to the Convention because they lack the same legal status as it. They acquire legal force once transposed into national law of States which may also be waived. For years, the non transposition of annexes in the positive law of states was tolerated. However, since the introduction of the system safety audits and safety, the lack of transposition may result in the placement of states on the secure site in the organization of the International Civil Aviation Organization (ICAO) and / or the list black of the European Union. By these two facts, the annexes have gained significant changes that impact the majority of states, particularly in Africa, where the rate of non-compliance with Schedules is the highest of all continents, what is wrong without consequence for aviation relations international and development industry of civil aviation for the African continent

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This thesis emerged from a question that had been repeating itself in my head for a long period of time: If myself and the rest of the world face the fact that we are likely to keep flying for years to come for reasons somehow considered valid, how can we at the same time still contribute efficiently to achieving a more sustainable future of aviation? Based on this dilemma and focusing on the factor of impact, an actor with the power of creating a larger impact than a single individual was firstly identified. This actor also provides the perspective used in this thesis. Meaning, the perspective of international companies that rely on flying for business for the purpose of surviving and thriving. The report’s purpose is to explore the opportunities and barriers for these companies with a will to contribute to the transformation to a future of sustainable aviation. The criteria of this company category are being both “international” and also “dependent” on business aviation. The term "international" in this context will later be defined and clarified, just as the definition of "dependent". Furthermore, this thesis is written based on an abductive literature study combined with a case study of an anonymous company located in Zürich, Switzerland. The Companyis included in the above category and could validate the hypothesis that companies like these exist through a series of interviews with employees.The validation of this hypothesis also paved the way to further explore the research questions on how these companies as customers can work both internally and externally with other stakeholders to enhance a Demand-Pull effect towards a more sustainable direction. It also discusses the Technology-Push effect from other stakeholders and its role in driving sustainable innovation development and implementation in technologies such as SAF, hydrogen and electric aviation. How to contribute to this large shift of an entire industry as a company that neither has expertise in sustainability nor aviation is exactly what is presented in the result, discussion and conclusion. Also, the possible consequences for a business and its employees that can follow by being involved and contribute to aviation sustainability. In addition, a mapping of awareness, knowledge gaps, motivation, and incentives has been done in order to identify the barriers and opportunities of the issue. / Detta arbete härstammar från en fråga som upprepat sig i mitt huvud under en längre tid: Om jag och resten av världen står inför det faktum att vi sannolikt kommer att fortsätta flyga i flera år framöver av skäl som på något sätt anses giltiga, hur kan vi samtidigt fortfarande bidra effektivt till att uppnå en mer hållbar framtid för flygindustrin? Utifrån detta dilemma och med fokus på hur man kan påverka som mest, identifierades först en aktör med kraften att skapa ett större genomslag än en enskild individ. Denna aktör bidrar också med det perspektiv som används i denna rapport. Det vill säga, perspektivet av internationella företag som är beroende av att flyga i affärssyfte för att överleva och växa. Syftet med rapporten är att utforska möjligheter och hinder för dessa företag med en vilja att bidra till omvandlingen till en framtid för hållbart flyg. Kriterierna för denna företagskategori är att vara både "internationell" och även "beroende" av affärsflyg. Termen "internationell" i detta sammanhang kommer senare att definieras och förtydligas, precis som definitionen av "beroende". Vidare är denna uppsats skriven baserat på en abduktiv litteraturstudie kombinerad med en fallstudie av ett anonymt företag beläget i Zürich, Schweiz. Företaget ingår i ovan nämnda kategori och kan därmed validera hypotesen att företag som dessa existerar genom en serie intervjuer utförda med anställda. Valideringen av denna hypotes banade också vägen för att ytterligare utforska frågeställningen om hur dessa företag som kunder kan arbeta både internt och externt med andra intressenter för att förstärka en Demand-Pull-effekt mot en mer hållbar riktning. Rapporten diskuterar också Technology-Push-effekten från andra intressenter och dess roll i att driva hållbar innovationsutveckling och implementering inom teknologier som SAF, vätgas och elflyg. Hur ett företag kan bidra till detta stora skifte av en hel bransch utan kompetens inom hållbarhet eller flyg är precis vad som presenteras i resultat, diskussion och slutsats. Även de möjliga konsekvenserna för ett företag och dess anställda som kan följa genom att vara delaktiga och bidra till flygindustrins hållbarhet. Slutligen, har en kartläggning av medvetenhet, kunskapsluckor, motivation och incitament gjorts i syfte att identifiera var möjliga hinder och möjligheter finns.