Abstracts: 2018-2019


Persistent, Historic Factors Correlated with Airport Bond Returns


Shivam Arora


The factors that are associated with returns on airport bonds are explored, using a proxy for an airport bond portfolio with the S&P Municipal Bond Airport Index. Six spread-based factors representing the tax status, term length, credit quality, bond type, infrastructure, and insurance status of airport bonds provide the independent variables. Five models are developed to test for bonds’ risk exposure to these characteristics and to analyze how these exposures for airport bonds differ from those of general transportation bonds or municipal bonds. Over 90% of the variation in returns on the airport index is explained by these factors. When determining risk premiums on airport bonds relative to other transportation bonds, investors appear to consider the bond type and infrastructure factors as being most relevant. However, when transportation bonds are compared with other municipal bonds, all factors except the insurance factor act as risk premiums. The component of airport bond returns not associated with these factors is partially explained by monthly changes in jet fuel prices and enplanements across all U.S. airports. These results can help airport bond issuers to evaluate the relative costs of raising funds through debt issues, and understand the trends in the bond market that are more strongly associated with prices and expected returns in the airport bond sector. Hedges against fuel price, enplanement changes, or both, may also be actions that airport bond issuers could consider outside of traditional financial planning practices to manage trends in the bond markets.


Optimization of Takeoff Departure Procedures for Airport Noise Mitigation


Ameya Behere and Dimitri N. Mavris


The environmental effects of aviation, particularly community noise exposure, is one of the major barriers to a sustainable growth in passenger air traffic. With an increasing number of aircraft operations and growing urban population, several major airports around the world have implemented various noise mitigation strategies. One such mitigation strategy is to optimize the departure procedures utilized by aircraft for performing takeoff operations. Present-day noise abatement departure procedures are developed by airlines under the guidance of the International Civil Aviation Organization and regulatory entities such as the Federal Aviation Administration. These procedures are generally limited to two per aircraft type and are therefore developed for averaged flight conditions. A generic methodology has been developed here which accounts for external parameters, such as the elevation and weather conditions at the departure airport, and aims to design optimal departure procedures per set of external conditions. By retaining these variables in the procedure design process, their influence on various metrics of interest can be studied. A case study is performed using three different airports each at a standard day and a hot day weather condition. Noise metrics are evaluated at four locations relative to the runway. Fuel consumption is also calculated to account for airline operating costs. The results show that the optimality of a procedure is sensitive on both external factors, as well as metrics being evaluated. While some noise metrics require a tradeoff with fuel consumption over a set of pareto optimal solutions, at certain locations, the two are optimized simultaneously by a single procedure.


Multiple-Case Study of U.S. General Aviation Airports for Operational Sustainability


Yue Gu and Mary E. Johnson


Improving operational sustainability may help U.S. general aviation (GA) airports improve overall sustainable development without substantial financial inputs. An exploratory multiple-case study of five GA airports was conducted to explore the current understandings of airport operational sustainability among U.S. GA airports. Based on findings, a new definition of airport operational sustainability for U.S. GA airports was developed. A set of performance metrics for measuring operational sustainability in U.S. GA airports was identified. The new definition may help GA airports to develop sustainable management plans, and may help airports in other categories to expand their sustainability perspectives. The metrics identified in this study may be used to measure progress to the sustainable development, identify problems, and set performance goals or targets for airports.


Building Information Modeling Implementation Framework for Smart Airport Life Cycle Management


Basak Keskin and Baris Salman


Connectivity is key in this new era of smart infrastructure. Smart airports utilize new connected technologies to improve end-user experience while ensuring operational feasibility in aeronautical and non-aeronautical segments. The increasing need for digitizing the design-build-operate life cycles of airports can be met by implementing building information modeling (BIM) that enables accessing, managing, utilizing, and connecting physical and operational data in a digital collaborative environment. This study investigates the current state of practice in airport BIM (ABIM) and the use of ABIM processes in digital airport operations and maintenance by connecting existing data sources and integrating smart airport systems. The study proposes a comprehensive and adaptive ABIM management framework that depicts the alignment and connectivity of ABIM processes, resources and stakeholders with airport operational requirements by identifying gaps in the industry and literature, and developing a global understanding in ABIM visions. Research data are collected through literature and industry review, online surveys, and semi-structured interviews with aviation professionals. Mixed methods including non-parametric statistical analysis and qualitative analysis are used to determine the elements of the framework. Model-based systems engineering (MBSE) principles and language are used to generate the framework. For framework validation, a proof of concept (POC) is conducted by development and deployment of a web-based application. The developed ABIM framework is expected to guide major airport stakeholders in their BIM implementation processes to enhance airport operational efficiencies and in strategizing digital initiatives on a connected-BIM platform.


Evaluation of Airport Wayfinding Accessibility with the Use of a Wheelchair Simulator


Zhu Qing, Carlos Sun, and Joseph Reneker


As the number of air passengers with disabilities is expected to increase in the coming decades, the significance of airport wayfinding accessibility has been recognized by airport stakeholders. Emerging assistive technologies have been used to accommodate passengers’ wayfinding needs; however, because of non-standard practices and the complexity of terminal designs, the literature only provides general guidance on improving airport wayfinding accessibility. There is a need for detailed analysis of quantitative traveler performance measures to evaluate airport wayfinding accessibility. This research is the first use of a wheelchair simulator to compare airport wayfinding signage with a mobile wayfinding application. A virtual model of the St. Louis Lambert International Airport main terminal was replicated using as-built computer-aided-design files. A federated simulation architecture was used to integrate the wheelchair simulator with a mobile wayfinding application. Wheelchair simulator experiments were conducted by analyzing twenty-four wheelchair users’ performance measures and eye tracking data. Although the mobile wayfinding application did not significantly reduce total travel time (–23.8 s) and deviation ratio (–3%), it reduced wheelchair users’ reliance on wayfinding signs by decreasing total glance frequency (–23.3 times) and total glance duration (–26.7 s) and helped to reduce travel anxiety in wheelchair users. The potential benefits of a mobile wayfinding application include improving traveler levels of service, reducing airport operating costs, and enhancing non-airline revenue. Overall, this study showed that, with the use of a wheelchair simulator, passenger performance could be captured and analyzed for evaluating the effectiveness of airport wayfinding accessibility and emerging assistive technologies.



Data-Driven Method to Study the Impact of Utilizing Electric Ground Power Systems on Airport Electricity Demand Profile


S.M. Sajed Sadati1 and Kristen S. Cetin


Gate electrification provides electricity and preconditioned air to stationary aircraft at airport gates as an alternative to the use of auxiliary power units. This includes a preconditioned air unit (PCA) and a ground power unit (GPU). This study aims to explore the impact of utilizing these units on the electricity demand of airports and analyzes the associated costs for both the cases of purchasing the electricity from a utility following a typical large commercial rate structure, and participating in the wholesale electricity market. The possibility of benefiting from solar energy to supply this electricity demand is also examined. The demand for gate electrification was measured at a gate at Des Moines International Airport in Iowa, U.S.A., and combined with other data including weather conditions and aircraft types to identify significant explanatory variables for electricity demand. This analysis revealed that ambient temperature is the main PCA demand predictor while aircraft type is the main factor driving the GPU demand. A linear regression model was developed to estimate the PCA electricity demand based on the ambient temperature. For the GPU, the typical demand was used based on aircraft type. This analysis shows that gate electrification used across all gates can contribute to up to 87% of the measured peak demand of the airport; the cost of participating in the wholesale market would be 57% less than following the current large commercial rate structure, and the airport can benefit from installing a photovoltaic system if the surplus electricity is utilized.


Automatic Communication Error Detection Using Speech Recognition and Linguistic Analysis for Proactive Control of Loss of Separation

Zhe Sun and Pingbo Tang


Losses of separation (LoS) are breaches of regulations that specify the minimum distance between aircraft in controlled airspace. Erroneous communications between air traffic controllers (ATCs) and pilots are leading contributors to LoS that result in elevated risk of fatal accidents. An air traffic control system that could identify communication errors promptly would, therefore, be advantageous. Establishing such a system requires a systematic characterization of communication errors to reveal how various communication arrangements and errors influence the development of LoS. Such know-how could guide the ATCs and pilots in identifying the parts of their communication processes and content that most influence the occurrence of LoS. Existing studies of LoS focus on simulation of aircraft operation processes with little quantitative analysis about how communication issues arise and result in elevated risks of LoS. This paper presents a method for supporting automatic communication error detection through integrated use of speech recognition, text analysis, and formal modeling of airport operational processes. The proposed method focuses on: identifying communication features to guide the detection of vulnerable communications; characterizing communication errors; and Bayesian Network modeling for predicting communication errors and LoS using the features derived from ATC–pilot communications. Major findings show that incorrect read-backs by pilots are highly correlated with a majority of LoS. Results indicate the proposed method could form a basis for automating communication error detection and preventing LoS. The integrated Automatic Speech Recognition and Natural Language Processing functions may be incorporated into existing aviation applications for real-time ATC–pilot communication monitoring and preventive LoS control.


Evaluating the Interoperability of Urban Air Mobility Systems and Airports


Parker D. Vascik and R. John Hansman


This paper investigates how existing arrival and departure procedures can be directly used or adapted to enable high-volume instrument and visual urban air mobility (UAM) flight operations at major airports in the United States. Viable procedures are restricted to those that enable simultaneous and non-interfering UAM flights with conventional aircraft operations. Air traffic controller workload is proposed as the critical integration barrier to scale UAM operations in visual conditions whereas separation minima, especially for approach procedures, is proposed as the critical barrier in instrument conditions. A systems approach is taken to evaluate potential integration strategies for UAM in which the location of UAM runways or vertipads and flight procedures are presented in a topological framework. The benefits, challenges, and notional application of five integration schemes are discussed. Four promising procedures for UAM are introduced through case studies at three airports. Findings indicate that multiple procedures exist to support high-volume UAM integration at major airports under current regulations with additional controller staffing, especially if UAM aircraft exhibit helicopter-like performance.


Mechanistic Modeling and Economic Analysis of Piezoelectric Energy Harvesting Potential in Airport Pavements


Jingnan Zhao and Hao Wang


This study investigated the feasibility of applying piezoelectric energy harvesting technology in airfield pavements through mechanistic modeling and economic analysis. The energy harvesting performance of piezoelectric transducers was evaluated based on mechanical energy induced by multi-wheel aircraft loading on flexible airfield pavements. A three-dimensional finite element model was used to estimate the stress pulse and magnitude under moving aircraft tire loading. A stack piezoelectric transducer design was used to estimate the power output of a piezoelectric harvester embedded at different locations and depths in the pavement. The aircraft load and speed were found to be vital factors affecting the power output, along with the installation depth and horizontal locations of the energy harvester. On the other hand, the installation of the energy module had a negligible influence on the horizontal tensile strains at the bottom of the asphalt layer and compressive strains on the top of the subgrade. However, the near-surface pavement strains increased when the edge ribs of the tire were loaded on the energy module. Feasibility analysis results showed that the calculated levelized cost of electricity was high in general, although it varies depending on the airport traffic levels and the service life of the energy module. With the development of piezoelectric materials and technology, further evaluation of energy harvesting applications at airports needs to be conducted.