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| Terminal Area Productivity (TAP) Program -- Taxi Navigation and Situation Awareness (T-NASA) System: 3-D Audio Ground Collision Avoidance System (GCAS) & Navigation System |
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Principal Investigators
Elizabeth M. Wenzel, Durand R. Begault
Abstract
The goal of the TAP Low-Visibility Landing and Surface Operations (LVLASO) subelement is to improve the efficiency of airport surface operations for commercial aircraft operating in weather conditions to Category IIIB while maintaining a high degree of safety. In TAP/LVLASO, advanced technologies such as satellite navigation systems, digital data communications, information presentation technology, and ground surveillance systems will be integrated into the flight deck to enable expeditious traffic movement on the airport surface. For TAP/LVLASO, the Flight Management and Human Factors Division at Ames Research Center is developing a cockpit display suite called the T- NASA (Taxi Navigation and Situation Awareness) System. This system has three integrated components: 1) Moving Map -- airport taxi chart with route, and own-ship and traffic location; 2) Scene- Linked Symbology -- route/taxi information virtually projected via a HUD onto the forward scene; and, 3) 3-D Audio Ground Collision Avoidance System (GCAS) and navigation system-- spatially localized auditory traffic and navigation alerts. Additionally, the Crew Roles and Procedures project is assessing the impact of these advanced technologies on the cockpit crew and controllers, as well as recommending procedure modifications as necessary.
Problem
In the terminal area context, low visibility (RVR 300) conditions result in slower taxi operations, resulting in a significant decrease in the efficiency in bringing aircraft in and out of the airport. Incursions from unseen vehicles, obstacles or aircraft are additional problems under low visibility. The workload of the flight crew and the information received from visual and auditory displays is at a maximum under these conditions.
Approach and Objectives
Broadly stated, the TAP initiative utilizes differential global position sensing (DGPS) to track aircraft and other vehicles on the ground, and then uses this information to provide visual and auditory situational awareness via advanced guidance systems and displays. A three-dimensional auditory display is used as a ground collision avoidance system (audio GCAS; Figure 1.1a). to provide immediate situational awareness about crossing runways, potential incursions, and when the aircraft is "off-track" (deviates from center line).
Accomplishments
A full-mission simulation study concluded in July, 1995, using 12 crews in a 747-400 simulator. We hypothesized that there would be a significant preference for an audio GCAS system to be included in the flight deck on the part of the pilots. We found significant preference favoring the audio GCAS system. The main conclusions of the study were that an audio GCAS system would be useful for avoiding potential incursions under both normal and low visibility conditions, and that an auditory system presenting incursion alerts would be a useful adjunct to a moving map display. We also found positive preference for the stereo headsets that were used to provide the 3-D audio cueing.
We also sought to determine ground taxi time under 3-D audio aided and unaided conditions. The aided condition featured a 3-D audio navigation system (Figure 1.1b) for orientation that called out specific taxiway turnoffs on the route. We hypothesized that this system would significantly reduce the time required for taxing to the gate, compared to a control condition where the crew uses only a paper map. The results showed no significant difference between conditions. An interesting outcome was a possibility of occupational-related hearing loss. 50 % of the respondents reported that they either suspected or were told by a doctor that they had permanent hearing loss. While presbycusis (loss of hearing as a result of old age) may have been a factor, the rate of permanent hearing loss for this age group should range from 6-16% of the population. The crew members had a much higher incidence than normal of tinnitus, the phenomenon often called "ringing" or "buzzing" in the ears; while among the general population, 15-32% have had tinnitus at some point and 5% are disabled by it, 50 % of the 24 pilots questioned reported tinnitus: 25% "occasionally", and 25% "frequently."
Future plans
We will gather data in an experiment scheduled for May 1996 on the integration of the 3-D audio GCAS system with the TAP visual display systems (head-down and head-up), within the T-NASA part-task simulator. Audio functions in addition to GCAS include:
active noise cancellation for conservation of hearing; an alert as to when the pilot turns too early, a problem observed in the initial study; audio reinforcement when approaching the "hold bar," possibly with proximity cues; calling out when approaching an active runway; alert when the pilot is over speed (15-20 knots on straight- aways, less for turns, for a Boeing 747-400).
Key references
Begault (1995). " 'Post-Mortem': Summary of Data Results and Recommendations 3-D Audio Experiment, CVSRF, 4.19.95-6.21.95" (internal white paper). Currently in preparation for submission to peer-reviewed journal as: Begault, Wenzel, Miller and Shrum, "Evaluation of a 3-D audio ground collision avoidance and navigation system."
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