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The Taxiway Navigation and Situation Awareness
(T-NASA) system is a suite of cockpit displays (composed
of a head-up display (HUD) and an electronic
moving map (EMM) as shown in figure 1) designed in
support of the Aero-Space Technology Enterprise
research objective to maintain safety while tripling
throughput in all weather conditions. The T-NASA
taxi HUD uses scene-linked symbology, superimposed
on the forward scene, to present taxi route
information, situational awareness information, and
ground speed. The EMM depicts the cleared taxi
route, as well as real-time information about own-ship
position, airport traffic, and hold-short locations.
The T-NASA system assumes that in the future taxi
clearances will be data linked, allowing for both a
textual and graphical representation in the cockpit,
improved taxi route conformance, and improved
traffic flow.
During FY99, our accomplishments included the
development and evaluation of two implementation
plans for integrating T-NASA into surface operations.
The Transition Implementation, designed to integrate
easily into near-term operations, required minimal
procedural and equipment modifications. The most
notable modification was the introduction of data-link
backup to ATC voice communications. The
Future Implementation promised greater efficiency
benefits, but required revolutionary modifications to
current operations such as the sole use of data link
for all routine ATC-pilot communications and the
introduction of airborne taxi clearances.
A series of focus groups and a high-fidelity
simulation conducted in Ames' Advanced Concept
Flight Simulator (ACFS) investigated the operational
issues associated with the Transition and Future
implementations of the T-NASA displays. The
simulation focused on issues raised during the focus
groups including the timing and format of taxi
clearances, pilot workload, situational awareness,
and complacency. Commercial airline crews (18)
completed 14 low-visibility (runway visual range
(RVR) of 1,000 feet) land-and-taxi scenarios that
included both nominal taxi events (such as hold-shorts
and route amendments) and off-nominal events
(such as near traffic incursions, clearance errors, and
display information inconsistencies). All crews
completed four baseline scenarios using current
standard operations and equipment. In addition,
crews completed 10 scenarios with either the Transition
Implementation (9 crews) or the Future Implementation
package (9 crews).
T-NASA increased taxi speeds by 16% (2.2 knots)
over present scenarios while simultaneously eliminating
major navigation errors (making a wrong turn,
failing to turn) which occurred in 20% of the present
scenarios. Further, the revolutionary changes embedded
in the Future Implementation package produced
large efficiency benefits. Specifically, when taxi
clearances were data linked to pilots while airborne
(outside outermarker), the time spent stopped after
runway turnoff was eliminated (saving approximately
10 seconds per trial), and taxi speeds during this
typical bottle-necked phase of taxiing increased by
approximately 78% (7.4 knots). Also, the Future
Implementation package provided substantial
improvements in ATC-pilot communication efficiency
by reducing radio congestion and communication
errors. These results suggest not only that
T-NASA can provide substantial benefits in terms of that
further gains may be realized by incorporating
revolutionary changes to surface operations such as
the use of data link and airborne taxi clearances.
Point of Contact: D. Foyle
(650) 604-3053
dfoyle@mail.arc.nasa.gov
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Fig. 1. T-NASA display suite integrated into NASA's
Advanced Concept Flight Simulator with insets of the
head-up display, data-link display, and electronic
moving map.
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