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Instead of being able to fly the most efficient
route to a destination, aircraft operators in today's air
traffic control system are usually constrained to
follow established airways that are often composed of
inefficient route segments. Current air traffic control
user-interface inefficiencies inhibit controllers from
issuing user-preferred routes, even under light traffic
conditions. The objective was to develop and
validate a controller tool that identifies and facilitates
time-saving direct routes in en route (or "Center")
airspace. The Direct-To Controller Tool identifies
aircraft that can save at least 1 minute flying time by
flying direct to a downstream fix along their route of
flight. A list ordered by time-savings is displayed on
the controller's monitor showing the call sign, time
savings, Direct-To fix, wind-corrected magnetic
heading to the fix, and conflict status for eligible
aircraft. A point-and-click button next to the call sign
on the Direct-To list activates a trial planning function
that allows the controller to quickly visualize the
direct route, choose a different fix if necessary, and
automatically input the direct route flight plan
amendment to the FAA Host computer. The Direct-To
Tool (shown in the figure) was implemented in the
Center-TRACON Automation System (CTAS) by
adding one additional module to the existing software
architecture for the Traffic Management Advisor
(TMA).
Accounting for the wind field is an essential
element of the Direct-To algorithm. The CTAS
trajectory synthesizer, with its hourly wind update
from National Oceanic and Atmospheric
Administration's Rapid Update Cycle atmospheric
model, compares flying time along the flight plan
route and the direct route to identify time-saving
routes. Candidate Direct-To fixes are restricted to be
within a limit rectangle (1,000 x 600 miles for Fort
Worth Center airspace) to prevent aircraft from
deviating significantly from planned routes. For large
airports within the limit region, where a direct route
to the airport is not feasible, Direct-To fixes are
limited to an appropriate fix along the arrival route to
the airport.
Analysis of Fort Worth Center traffic data shows a
potential average saving of 1,800 minutes flying time
per day or about 2.5 minutes per Direct-To aircraft. A
controller simulation of Direct-To was conducted at
Ames in August 1999. Controller feedback was very
favorable and the Fort Worth Center controller team
felt the tool was ready for field-test evaluation. A
functional test of the Direct-To Tool integrated with
the Center Host computer was conducted at the FAA
Technical Center in June 1999. The point-and-click
flight plan amendment capability was demonstrated
with only minor changes (three lines of code) to the
CTAS/Host interface software. A provisional patent
application has been filed. Future plans call for field-test
evaluation of the Direct-To Tool at Fort Worth
Center.
Point of Contact: D. McNally
(650) 604-5440
dmcnally@mail.arc.nasa.gov
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Fig. 1. Direct-To Controller Tool.
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