Home' RTCA Documents for Review : DO-220A Change 1 Contents Appendix A
DO-220A Change 1
© 2018 RTCA, Inc.
FORWARD-LOOKING WINDSHEAR TEST CASES
General Windshear Scenario Test Information
These testing scenarios are chosen to evaluate the system's detection capability in a variety
of situations. Each is different enough from each other in terms of airplane configuration,
altitude, pitch angle, and windshear location that it would be difficult to infer acceptable
system performance by a more limited testing matrix. The testing matrix distributes the
possible combination of conditions, e.g. wind field models, airspeeds, intervening rain,
etc., to critical flight phases in lieu of applying all combinations to all flight phases.
Radar system manufacturers are expected to certify the windshear system
detection performance using a radome one level below the lowest in-service
radome level. This is to account for expected degradation of the radome during
All tests should include considerations for the worse case transmissivity loss
(within the total loss budget) and representative sidelobe magnitude and
directivity characteristics associated with the class and category of radome
desired for certification approval (see RTCA/DO-213, [G-2]).
If the atmosphere outside of the local environment of these models affects the
detection schemes, take this into account when demonstrating windshear
detection, e.g. temperature lapse rate history during approach.
Microbursts are static during each simulation run.
Paths are specified by direction of takeoff or approach, X or Y coordinate of
flight path, and runway threshold coordinates.
Scenario FBARs, reflectivities and velocities are along the aircraft’s three -
dimensional flight path. For example, for straight-in approach scenarios they
are along the -3 -degree glide slope.
Coordinates are specified with respect to the microburst data set. Positive X is
true east; positive Y is true north; positive Z is altitude above ground. All
coordinates are expressed in metric units.
The NASA windshear database models [W-9] and ADWRS [W-10] can be found with the
latest revision of TSO-C63 on the FAA internet website “Regulatory and Guidance
Library” at http://rgl.faa.gov/.
Considerations Associated with the Use of The Windshear Test Set-Up
The test set-up recommended for use in determination of windshear performance is
developed around an adaptation of the NASA Langley Research Center's Airborne Doppler
Weather Radar Simulation (ADWRS) program.
The ADWRS FORTRAN program calculates the range-Doppler return for system
parameters of a coherent airborne radar. The simulation consists of a number of fine steps-
in-time corresponding to coherent processing intervals (CPI). For each CPI, the aircraft
position and antenna scan position are updated and then held constant for subsequent pulses
within the CPI. The amplitude and phase of the resultant signal for each range gate (receiver
matched time sample in inter-pulse time respective of transmit time) are the vectoral (phase
and amplitude) sum of the scattered radar signal for incremental volume and area scatterers.
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