Air Transportation And Socioeconomic Connectivity In The United States Since Deregulation

In light of ongoing threats to the viability of traditional airline business models and the provision of air service in the United States, this paper studies the fundamental interdependence of the national economy and the air transportation system. A conceptual framework has been developed to identify the mechanisms that enable air transportation to shape regional economic productivity and social connectivity. Regional economic census data is combined with airline traffic and financial data to illustrate the changes in supply and demand for air travel after the deregulation of the airline industry in 1978. The paper focuses on how the utilization of air transportation system supports economic and social activities across greater distances than would otherwise be possible—changing the economic geography of market access. An analysis of industry restructuring after the economic bubble and the attacks of September 11, 2001 are also used to look at the potential impacts on economic activity at the regional and national levels

Use of Structure as a Basis for Abstraction in Air Traffic Control

The safety and efficiency of the air traffic control domain is highly dependent on the capabilities and limitations of its human controllers. Past research has indicated that structure provided by the airspace and procedures could aid in simplifying the controllers cognitive tasks. In this paper, observations, interviews, voice command data analyses, and radar analyses were conducted at and using data from the Boston Terminal Route Control (TRACON) facility to determine if there was evidence of controllers using structure to simplify their cognitive processes. The data suggest that controllers do use structure-based abstractions to simplify their cognitive processes, particularly the projection task. These structure-based abstractions were outlined and their effect on various ATC cognitive processes were discussed. Suggestions for the design of future ATC information tools were provided based on the findings from this study.This research was supported by NASA, FAA, and the Beinecke Brothers Memorial Scholarship

Observations and Potential Impacts of Regional Jet Operating Trends

Airlines are increasingly using regional jets to better match aircraft size to high value demand markets, and reduce labor costs. This has been especially important due to the increased pressure on the industry following September 11th 2001, because airlines see regional jets as a major part of their financial recovery plan. The increase in regional jets represents a significant change from traditional air traffic patterns and airline business models. To investigate the possible impacts of this change, this study analyzed the economic characteristics of regional jets, and well as the emerging flight patterns and performance of regional jets compared to traditional jets and turboprops. It was found that regional airlines have lower crew costs per number of block hours and take offs, but higher crew cost per ASMs and RPMs. As a result, the revenues at regional airlines are more susceptible to changes in crew cost. It was also observed that regional jets operate differently then traditional jets. Regional jets increase the number of operations at airports and in the take off tracks around airports, which may result in increased congestion. Regional jets were also observed to exhibit lower climb rates than traditional jets, which may negatively impact air traffic control handling and sector design. Given the possible economic and operational problems associated with regional jets, their growth may pose unanticipated problems

Supporting the Future Air Traffic Control Projection Process

In air traffic control, projecting what the air traffic situation will be over the next 30 seconds to 30 minutes is a key process in identifying conflicts that may arise so that evasive action can be taken upon discovery of these conflicts. A series of field visits in the Boston and New York terminal radar approach control (TRACON) facilities and in the oceanic air traffic control facilities in New York and Reykjavik, Iceland were conducted to investigate the projection process in two different ATC domains. The results from the site visits suggest that two types of projection are currently used in ATC tasks, depending on the type of separation minima and/or traffic restriction and information display used by the controller. As technologies improve and procedures change, care should be taken by designers to support projection through displays, automation, and procedures. It is critical to prevent time/space mismatches between interfaces and restrictions. Existing structure in traffic dynamics could be utilized to provide controllers with useful behavioral models on which to build projections. Subtle structure that the controllers are unable to internalize could be incorporated into an ATC projection aid

Impact of Air Transportation on Regional Economic and Social Connectivity in the United States

This paper identifies some of the forces that influence the impact of air transportation on regional connectivity and economic productivity in the United States. In light of recent threats to the financial viability of the airline industry, a conceptual model has been developed to highlight the interdependence of the national economy and the air transportation system. These complex relationships are identified using regional economic and social indicators combined with airline traffic and financial data. The changes in supply and demand for air travel after the deregulation of the airline industry in 1978—as well as the challenges faced after the attacks of September 11, 2001—are used to frame this discussion.Alfred P. Sloan Foundatio

The interaction of radio frequency electromagnetic fields with atmospheric water droplets and applications to aircraft ice prevention

The feasibility of computerized simulation of the physics of advanced microwave anti-icing systems, which preheat impinging supercooled water droplets prior to impact, was investigated. Theoretical and experimental work performed to create a physically realistic simulation is described. The behavior of the absorption cross section for melting ice particles was measured by a resonant cavity technique and found to agree with theoretical predictions. Values of the dielectric parameters of supercooled water were measured by a similar technique at lambda = 2.82 cm down to -17 C. The hydrodynamic behavior of accelerated water droplets was studied photograhically in a wind tunnel. Droplets were found to initially deform as oblate spheroids and to eventually become unstable and break up in Bessel function modes for large values of acceleration or droplet size. This confirms the theory as to the maximum stable droplet size in the atmosphere. A computer code which predicts droplet trajectories in an arbitrary flow field was written and confirmed experimentally. The results were consolidated into a simulation to study the heating by electromagnetic fields of droplets impinging onto an object such as an airfoil. It was determined that there is sufficient time to heat droplets prior to impact for typical parameter values. Design curves for such a system are presented

Investigating Conformance Monitoring Issues in Air Traffic Control Using Fault Detection Approaches

In order to maintain Air Traffic Control (ATC) system safety, security and efficiency, conformance monitoring must be performed to ensure that aircraft adhere to their assigned clearances. New Decision Support Tools (DSTs), coupled to advanced communication, navigation and surveillance technologies are being developed which may enable more effective conformance monitoring to be undertaken relative to today. However, there are currently no general analysis techniques to help identify fundamental conformance monitoring issues and more effective approaches that new DSTs should employ. An approach to address this need is presented in this work that draws parallels between ATC conformance monitoring and general system fault detection, allowing fault detection methods developed for other domains to be employed for this new application. The resulting Conformance Monitoring Analysis Framework provides a structure to research conformance monitoring issues and approaches. Detailed discussions are presented for each of the elements of the framework, including the Conformance Basis, Actual System Representation, Conformance Monitoring Model, Conformance Residual Generation and Decision-Making components. Flight test data during a simple lateral non-conformance maneuver was used to demonstrate various implementation options of the framework. Application of the framework for ATC conformance monitoring research was demonstrated using flight test and simulator data in various operational and surveillance environments. Key findings in the lateral, vertical and longitudinal domains during non-transitioning and transitioning flight regimes are presented. In general, it was found that more effective conformance monitoring can be conducted relative to existing systems in the non-transitioning environments when advanced surveillance systems provide higher accuracy, higher update rate and higher order dynamic state information for use in more sophisticated DST algorithms. This is contrasted to the significantly greater conformance monitoring challenges that exist in the transitioning regimes due to Conformance Basis and modeling uncertainties. These challenges can be handled through the use of procedural design, higher fidelity modeling techniques or the surveillance of intent states. Two extended applications of the framework are also presented: a method for intent inferencing to determine what alternative trajectory a non-conforming aircraft may be following and a technique for environmental parameter estimation.This work was funded by the NASA Langley Research Center under grant NAG1-02006. Sincere thanks to Richard Barhydt & Mark Ballin for their support through this grant. The authors would also like to thank Mike Paglione at the FAA Technical Center and Len Tobias at the NASA Ames Research Center for earlier support through the FAA/NASA Joint University Program under grant FAA95-G-017

Emergence of Regional Jets and The Implications on Air Traffic Management

Airlines are increasingly using regional jets to better match aircraft size to high value, but limited demand markets. This has been especially important following increased financial pressure on the industry after September 11th 2001. The increase in regional jets represents a significant change from traditional air traffic patterns. To investigate the possible impacts of this change, this study analyzed the emerging flight patterns and performance of regional jets compared to traditional jets and turboprops. In addition, a comparison between regional jet flight patterns in the United States and Europe was conducted. Regional jet operations generally cluster in the regions with high traditional jet operation density, implying a high level of interaction between the two aircraft types. The regional jets were observed to fly shorter routes than traditional jets, with few transcontinental flights. However, the gap between regional and narrow body traditional jet stage lengths appears to be closing. In addition, regional jets were observed to exhibit lower climb rates than traditional jets, which may impact air traffic control handling and sector design. It was also observed that regional jets cruise at lower altitudes than traditional jets possibly due to their shorter flight routes. Finally, it was observed that regional jets cruise at a lower Mach number than traditional jets, except on specific high density routes where the regional jets are either slowing down the traditional jet traffic or flying above their optimum cruise speed. Since the composition and utilization of the national fleet is changing, this will pose potential problems for air traffic management. In particular, it may cause serious congestion issues when demand increases during an economic recovery

The Impact of GPS Velocity Based Flight Control on Flight Instrumentation Architecture

This thesis explores the use of velocity information obtained by a Global Positioning System (GPS) receiver to close the aircraft’s flight control loop. A novel framework to synthesize attitude information from GPS velocity vector measurements is discussed. The framework combines the benefits of high-quality GPS velocity measurements with a novel velocity vector based flight control paradigm to provide a means for the human operator or autopilot to close the aircraft flight control loop. Issues arising from limitations in GPS as well as the presence of a human in the aircraft control loop are addressed. Results from several flight tests demonstrate the viability of this novel concept and show that GPS velocity based attitude allows for equivalent aircraft control as traditional attitude. Two possible applications of GPS velocity based attitude, an autopilot and a tunnelin- the-sky trajectory guidance system, are demonstrated in flight. Unlike traditional autopilot and trajectory guidance systems, these applications rely solely on the information obtained from a single-antenna GPS receiver which makes them affordable to the larger General Aviation aircraft community. Finally, the impact of GPS velocity based flight control on the instrumentation architecture of flight vehicles is investigated.Rockwell-Collins, NASA/FAA Joint University Program for Air Transportation, Draper Laborator

Heat Transfer Measurements on Surfaces with Natural Ice Castings and Modeled Roughness

An experimental method is described to measure and compare the convective heat transfer coefficient of natural and simulated ice accretion roughness and to provide a rational means for determining accretion-related enhanced heat transfer coefficients. The natural ice accretion roughness was a sample casting made from accretions at the NASA Lewis Icing Research Tunnel (IRT). One of these castings was modeled using a Spectral Estimation Technique (SET) to produce three roughness elements patterns that simulate the actual accretion. All four samples were tested in a flat-plate boundary layer at angle of attack in a "dry" wind tunnel test. The convective heat transfer coefficient was measured using infrared thermography. It is shown that, dispite some problems in the current data set, the method does show considerable promise in determining roughness-induced heat transfer coefficients, and that, in addition to the roughness height and spacing in the flow direction, the concentration and spacing of elements in the spanwise direction are important parameters