Maria C. Consiglio

Safety Performance of Airborne Separation: Preliminary Baseline Testing

The Safety Performance of Airborne Separation (SPAS) study is a suite of Monte Carlo simulation experiments designed to analyze and quantify safety behavior of airborne separation. This paper presents results of preliminary baseline testing. The preliminary baseline scenario is designed to be very challenging, consisting of randomized routes in generic high-density airspace in which all aircraft are constrained to the same flight level. Sustained traffic density is varied from approximately 3 to 15 aircraft per 10,000 square miles, approximating up to about 5 times today’s traffic density in a typical sector. Research at high traffic densities and at multiple flight levels are planned within the next two years. Basic safety metrics for aircraft separation are collected and analyzed. During the progression of experiments, various errors, uncertainties, delays, and other variables potentially impacting system safety will be incrementally introduced to analyze the effect on safety of the individual factors as well as their interaction and collective effect. In this paper we report the results of the first experiment that addresses the preliminary baseline condition tested over a range of traffic densities. Early results at five times the typical traffic density in today’s NAS indicate that, under the assumptions of this study, airborne separation can be safely performed. In addition, we report on initial observations from an exploration of four additional factors tested at a single traffic density: broadcast surveillance signal interference, extent of intent sharing, pilot delay, and wind prediction error.

Comparison of Ground-Based and Airborne Function Allocation Concepts for NextGen Using Human-In-The-Loop Simulations

Investigation of function allocation for the Next Generation Air Transportation System is being conducted by the National Aeronautics and Space Administration (NASA). To provide insight on comparability of different function allocations for separation assurance, two human-in-the-loop simulation experiments were conducted on homogeneous airborne and ground-based approaches to four-dimensional trajectory-based operations, one referred to as ground-based automated separation assurance (groundbased) and the other as airborne trajectory management with self-separation (airborne). In the coordinated simulations at NASA s Ames and Langley Research Centers, controllers for the ground-based concept at Ames and pilots for the airborne concept at Langley managed the same traffic scenarios using the two different concepts. The common scenarios represented a significant increase in airspace demand over current operations. Using common independent variables, the simulations varied traffic density, scheduling constraints, and the timing of trajectory change events. Common metrics were collected to enable a comparison of relevant results. Where comparisons were possible, no substantial differences in performance or operator acceptability were observed. Mean schedule conformance and flight path deviation were considered adequate for both approaches. Conflict detection warning times and resolution times were mostly adequate, but certain conflict situations were detected too late to be resolved in a timely manner. This led to some situations in which safety was compromised and/or workload was rated as being unacceptable in both experiments. Operators acknowledged these issues in their responses and ratings but gave generally positive assessments of the respective concept and operations they experienced. Future studies will evaluate technical improvements and procedural enhancements to achieve the required level of safety and acceptability and will investigate the integration of airborne and ground-based capabilities within the same airspace to leverage the benefits of each concept.

Impact of Pilot Delay and Non-Responsiveness on the Safety Performance of Airborne Separation

Assessing the safety effects of prediction errors and uncertainty on automation supported functions in the Next Generation Air Transportation System concept of operations is of foremost importance, particularly safety critical functions such as separation that involve human decision-making. Both ground-based and airborne, the automation of separation functions must be designed to account for, and mitigate the impact of, information uncertainty and varying human response. This paper describes an experiment that addresses the potential impact of operator delay when interacting with separation support systems. In this study, we evaluated an airborne separation capability operated by a simulated pilot. The experimental runs are part of the Safety Performance of Airborne Separation (SPAS) experiment suite that examines the safety implications of prediction errors and system uncertainties on airborne separation assistance systems. Pilot actions required by the airborne separation automation to resolve traffic conflicts were delayed within a wide range, varying from five to 240 seconds while a percentage of randomly selected pilots were programmed to completely miss the conflict alerts and therefore take no action. Results indicate that the strategic Airborne Separation Assistance System (ASAS) functions exercised in the experiment can sustain pilot response delays of up to 90 seconds and more, depending on the traffic density. However, when pilots or operators fail to respond to conflict alerts the safety effects are substantial, particularly at higher traffic densities

DAIDALUS: Detect and Avoid Alerting Logic for Unmanned Systems

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

IFR Operations at Non-Towered, Non-Radar Airports: Can we do Better Than One-at-a-Time?

This paper describes a new concept for operations in non-radar terminal airspace around small, nontowered airports. Currently, air traffic operations in instrument meteorological conditions (IMC) at airfields without control towers and radar service are severely constrained by what is known as the one-in/one-out paradigm. Under these conditions only one operation (either arrival or departure) is allowed to occur at a time. Since these operations can take over 15 minutes to complete, capacity at these airports is severely restricted in IMC. The proposed concept is an attempt to break this current paradigm by applying emerging airborne and ground-based technologies to enable simultaneous operations by multiple aircraft in nonradar terminal airspace around small non-towered airports in IMC. The general philosophy underlying this concept of operations is the establishment of a newly defined area surrounding these airports called a Self-Controlled Area (SCA). Aircraft operating within the SCA are required to have a specified minimum level of equipage. Within the SCA, pilots are responsible for separating themselves from other similarly equipped aircraft through the use of new onboard systems and procedures. This concept also takes advantage of newly developed automation at the airport, which provides appropriate sequencing information to the pilots for safe and improved operations. Such operations would enhance the opportunity for point-to-point air taxi or charter operations into smaller airfields that are closer to a traveler s origin and destination. A description of this concept of operations and a simulation environment used for evaluation is provided in this paper.

The pilot advisor: assessing the need for a procedural advisory tool

One objective of the small aircraft transportation system (SATS) higher volume operations (HVO) project is to increase the capacity and utilization of small nontowered, nonradar equipped airports by transferring sequencing and separation responsibilities to general aviation (GA) pilots supported by a ground based automated airport management module (AMM) (Abbott et al., 2004), The AMM sequences traffic into the self-controlled area, a newly defined volume of airspace around a SATS airport. ADS-B, broadcast among participating aircraft, would provide the data necessary for informing the pilot of aircraft position and display that traffic on a multi-function display (MFD). An important aspect of the concept included tools that would aid the pilot in self-separation tasks, flying within a containment area along the approach path and alerting the pilot to potential conflicts. Interactive communications between aircraft and the AMM were displayed via dynamic messaging windows, one of which was the pilot advisor (PA). This paper discusses the experiment designed to determine the utility of the pilot advisor in self-separation.

Flight technical error analysis of the SATS higher volume operations simulation and flight experiments

This paper provides an analysis of flight technical error (FTE) from recent SATS experiments, called the higher volume operations (HVO) simulation and flight experiments, which NASA conducted to determine pilot acceptability of the HVO concept for normal operating conditions. Reported are FTE results from simulation and flight experiment data indicating the SATS HVO concept is viable and acceptable to low-time instrument rated pilots when compared with todays system (Baseline). Described is the comparative FTE analysis of lateral, vertical, and airspeed deviations from the Baseline and SATS HVO experimental flight procedures. Based on FTE analysis, all evaluation subjects, low-time instrument-rated pilots, flew the HVO procedures safely and proficiently in comparison to todays system (Baseline). In all cases, the results of the flight experiment validated the results of the simulation experiment and confirm the utility of the simulation platform for comparative human in the loop (HITL) studies of SATS HVO and Baseline operations.

Small Aircraft Transportation System, Higher Volume Operations Concept and Research Summary

Described is the research process that NASA researchers used to validate the Small Aircraft Transportation System (SATS) Higher Volume Operations (HVO) concept. The four phase building-block validation and verification process included multiple elements ranging from formal analysis of HVO procedures to flight test, to full-system architecture prototype that was successfully shown to the public at the June 2005 SATS Technical Demonstration in Danville, VA. Presented are significant results of each of the four research phases that extend early results presented at ICAS 2004. HVO study results have been incorporated into the development of the Next Generation Air Transportation System (NGATS) vision and offer a validated concept to provide a significant portion of the 3X capacity improvement sought after in the United States National Airspace System (NAS).The ability to conduct concurrent, multiple aircraft operations in poor weather at virtually any airport offers an important opportunity for a significant increase in the rate of flight operations, a major improvement in passenger convenience, and the potential to foster growth of operations at small airports. The Small Aircraft Transportation System (SATS), Higher Volume Operations (HVO) concept is designed to increase capacity at the 3400 nonradar, non-towered airports in the United States where operations are currently restricted to “one-in/one-out” procedural separation during low visibility or ceilings. The concept’s key feature is that pilots maintain their own separation from other aircraft using air-to-air datalink and on-board software within the Self-Controlled Area (SCA), an area of flight operations established during poor visibility and low ceilings around an airport without Air Traffic Control (ATC) services. While pilots self-separate within the SCA, an Airport Management Module (AMM) located at the airport assigns arriving pilots their sequence based on aircraft performance, position, winds, missed approach requirements, and ATC intent. The HVO design uses distributed decision-making, safe procedures, attempts to minimize pilot and controller workload, and integrates with today’s ATC environment. This paper summarizes the HVO concept and procedures, presents a summary of the research conducted and results, and outlines areas where future HVO research is required.

Conflict Prevention and Separation Assurance in Small Aircraft Transportation Systems

A multilayer approach to the prevention of conflicts due to the loss of aircraft-to-aircraft separation that relies on procedures and onboard automation was implemented as part of the Small Aircraft Transportation Systems Higher-Volume-Operations concept. The multilayer system gives pilots support and guidance during the execution of normal operations and advance warning for procedure deviations or off-nominal operations. This paper describes the major concept elements of this multilayer approach to separation assurance and conflict prevention and provides the rationale for its design. All the algorithms and functionality described in this paper were implemented in an aircraft simulation in the Air Traffic Operations Laboratory at NASA Langley Research Center and on the NASA Cirrus SR22 research aircraft.

SATS HVO procedures for priority landings and mixed VFR/IFR operations

This paper describes a pilot in the loop simulation experiment of the small aircraft transportation system (SATS) higher volume operations (HVO) concept for off-nominal conditions conducted at the Air Traffic Operations Lab (ATOL), NASA Langley Research Center. The experiment was designed to validate procedures for priority landing requests and pilot cancellations of approach requests with subsequent transitions to visual flight rules (VFR). Priority landing requests during approach operations allow pilots to land ahead of others in the sequence. Cancellations of approach requests allow participating aircraft to cancel an approach sequence and transition to VFR if desired. Preliminary results show that pilots find the procedures acceptable with no increase in perceived workload as compared to nominal SATS HVO operations while pilot performance and situation awareness metrics are consistently high. Overall, subject pilots welcome the increased potential efficiency the concept offers and the increased ability to self-control while flying SATS HVO procedures.