Sherry Borener

Analysis of the effects of communication and surveillance facility service outages on traffic separations

This study examines air traffic separations in the service volumes of communication and surveillance facilities that experienced service outages. The data sample consists of 338 unscheduled service outages that happened in 2010 and 2011 at facilities located in the vicinity of 15 major traffic hubs. For each outage, radar track data were collected and used to calculate traffic separations during the period of 30 minutes before to 30 minutes after an outage. Then, the separation index, which indicates the percentage of horizontal separation retained between two aircraft at the same altitude, was estimated. The separation index and loss of separation events were analyzed using lognormal and negative binomial regression models. The results suggest that the count of separation events peaks during the 15 minutes after an outage. In addition, traffic collision avoidance system resolution advisory (TCAS RA) encounters and Category A separation events are 1.31 times more likely during the 30 minutes following the beginning of a service outage, as compared to the 30 minutes before the outage, for both types of facilities. Also, the separation index values are 19% lower following a surveillance facility outage and 4% lower following a communication facility service loss. This study provides evidence that unscheduled service outages of air traffic management facilities are associated with lost or reduced traffic separations and thus can be considered precursors to hazardous loss of separation events.

Analysis of s-turn approaches at John F. Kennedy Airport

This study analyzed tracking data for arrival flights to John F. Kennedy International Airport (JFK) during the period of August 16 to August 21, 2009 to identify s-turn maneuvers and to characterize s-turn trajectories. The s-turn maneuver appears in the tracking data as a sequence of turns alternating in heading range. S-turns can arise as an alternative path stretching technique to vectoring and holding. This study developed analysis algorithms and associated metrics to automatically assess the occurrence conditions and operational impact of s-turn trajectories, and determined they (1) exhibit terminal airspace transit times several minutes greater than non s-turn trajectories, (2) occur in all runway-metering fix combinations, (3) occur in merging and in-trail flight conditions, (4) occur at numerous distances from the airport, (5) do not exhibit significantly different inter-flight time spacing at the runway, and (6) the lateral spatial extent of s-turn maneuvers can be quite large. Analysis remains to assess the separation of s-turn trajectories from others throughout the maneuver, and to identify and characterize other such flight maneuvers and behavior in terminal airspace.

Effects of 3D Time-Harmonic Gust and Turbulence on Unsteady Aerodynamic Responses of Loaded Low-Speed Airfoils

The objective of the current work is to compare variable-fidelity approaches for predictions of unsteady airfoil lift induced by an impinging turbulence based on the superposition of timeharmonic vortical gusts. First, analytical models are reviewed describing 2D, inviscid, timeharmonic gust-airfoil modal interactions. A low-fidelity model is then developed to predict the upstream turbulence response synthesized using a superposition of gust responses and based on the random flow generation (RFG) procedure. Finally, the results obtained using the proposed analytical inviscid model are compared against high-fidelity viscous simulations performed for NACA0012 and SD7003 airfoils.

Analysis of safety implications for SJA-based robust UAS flight control technology

This article consists of a collection of slides from the authors conference presentation.

Causality of surface movement anomalies at KJFK airport

The FAA/ASIAS Office and the Saab Sensis Corporation developed a system for the automated detection and evaluation of unusual or anomalous movements of aircraft taxiing on the airport surface. These anomalies may be precursors to safety incidents and may also indicate conditions leading to reductions in airport operational efficiency. This paper presents two case studies based on the data produced by the automated anomaly detection and scoring system; the case studies validate the system and explore causes of anomalies. Specifically, the relationship between frequency of anomaly occurrence and surface congestion is explored and a study of the relationship between the rate of occurrence of sudden-stop (SST) anomalies and other factors, including runway configuration and time-of-year, is undertaken. The paper discusses the role of automated anomaly detection in the development of safety management systems and the evaluation of benefits and risks of technology (e.g., moving map display) that may be deployed to mitigate anomaly occurrence and to improve airport operational safety and efficiency.