Air Traffic Management Concept Baseline Definition - The Boeing ...

longer-term domestic and international forecasts are made using codes such as the AVN
and MRF prognostic models. Forecasts are usually issued in three to six hour intervals for
periods as short as three hours to as long as several days. AWC meteorologists use these
forecast products and other available information to prepare Terminal Aerodrome
Forecasts for U.S. airports, and to prepare advisories and alerts for weather conditions
that may adversely affect aviation operations (e.g., SIGMETS and convective SIGMETs).
In their present forms, models like the Eta and its counterparts are best suited for
predicting the movement of synoptic scale meteorological features that affect the weather
over regions larger than individual terminal areas and on time scales longer than are
valuable for many aircraft operations. Thus, while these models are useful for general
large-scale weather prediction, they have not been optimized to meet the specific needs of
the aviation weather system. The FAA, NASA, MIT-LL, NOAA, and NCAR have been
working on several new technologies designed to provide aviation-specific forecasts.
FSL has developed an analysis and forecasting tool called the Mesoscale Analysis and
Prediction System, which has been recently implemented at NCEP as the Rapid Update
Cycle (RUC). The RUC combines objective analyses and short-term (less than 12 hr.)
prediction tools to prepare gridded data sets of surface and upper-air meteorological
conditions that affect aviation operations. The RUC is run at NCEP every three hours on
a 60-km grid covering the CONUS, and produces an analysis of current conditions and 3-
hourly forecasts out to 12 hours. An experimental 40 km version is being tested, and
plans call for going to finer horizontal resolutions in the future.
RUC products are currently being tested in new CNS/ATM and aviation weather
technologies. For example, the current implementation of CTAS uses the 3D RUC wind
fields to calculate aircraft descent trajectories. An important issue for the successful
application of RUC data in CNS technologies like CTAS, Conflict Probe, and other flight
management systems is the need for good information on the accuracy and repeatability of
RUC variables (e.g., rms errors in upper-air wind analyses and forecasts). For example,
some preliminary evaluations of RUC upper-air wind forecasts indicate that in the 0-1 hr.
time frame rms errors in vector winds may be on the order of 2-3 m/s, increasing to 5-7
m/s at the end of the RUC forecast period. Likewise, the sensitivity of CNS/ATM
technologies to uncertainties in RUC variables needs to be examined. More information is
also needed on how RUC data sets will be incorporated into the AGFS.
The ITWS is an analysis and prediction tool that is currently being developed by MIT-LL
for use in the terminal area. The ITWS ingests the RUC gridded wind fields, TDWR and
NEXRAD wind data, ASR-9 weather reflectivity data, MDCRS observations,
ASOS/AWOS and LLWAS data, and other available information. It analyses these data
to determine storm cell locations and movement, areas of precipitation, locations and
intensities of gust fronts and microbursts, low-level winds affecting runway operations,
locations of tornadoes, and other aviation impact variables. It predicts storm cell
movement and the locations of gust fronts at 10 minute and 20 minute intervals from the
analysis time. ITWS also produces three-dimensional gridded fields of winds on scales
varying from 2 km near the terminal area to 60 km at the outer extent of the ITWS
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