Technical data

Product Specification
HIF-2121/R5 CAGE CODE: 97896 SCALE: NONE SIZE: A DWG NO: 965-1176-601 REV: D SHEET 83
6.5 MKVIII Windshear Detection Alerts
Revision History
Effectivity
Date - Modified By Description of the Updates App. Cfg.
29-NOV-99 Peter Bateman Initial Release and entry into PVCS. -001 -001
06-JUN-00 – Susie Wright Document only change – Deleted proprietary note from footer. -003 -003
02-JUL-01 – S. Wright SCR 4734: Added Honeywell windshear for BD-100 -008 -008
Windshear detection and annunciation is available for limited aircraft with the Mk VIII EGPWS installed. The status of the
windshear function is indicated by a windshear INOP output. Both a discrete lamp driver type output, and an ARINC 429
output bit provide this information. The discrete (lamp driver) output is designed to bias itself on in the event of power loss to
the EGPWC.
Windshear Caution disable and Windshear Caution Voice disable options are provided for those installations that disable the
windshear caution but preserve the windshear warning.
6.5.1 Honeywell Windshear Detection
Figure 6.5.1-1 presents an overall view of the windshear mode. The IRS/AHRS provides acceleration values along the body
axis. These accelerations are transformed to the air mass axis by using body angle of attack (AOA) and are then compared to
the atmospheric data from altitude rate and airspeed. The resultant windshear output is gain controlled as a function of
altitude, and roll attitude, before producing the detected shear output for the caution/warning logic.
The nominal windshear warning threshold is adjusted, or biased, as a function of numerous conditions. Air mass flight path
angle (gamma) is used to bias the threshold, as are abnormal temperature conditions in the atmosphere. In addition, the
amount of excess dynamic pressure (Q) is also used to bias the threshold. Aircraft type (currently only the BD-100) is used
to select the proper nominal windshear threshold, before the bias values are applied. Windshear enable logic determines the
validity, and suitability, of the resultant windshear caution, or warning, that is observed through the output logic.
ACCELERATION
(AOA TRANSLATED)
ALTITUDE RATE
CORRECTED AIRSPEED
RADIO ALTITUDE
ROLL ATTITUDE
AIRCRAFT TYPE
TAKEOFF BIAS
WINDSHEAR ENABLE LOGIC
GAMMA
WINDSHEAR
COMPUTATION
ALTITUDE RATE
STATIC AIR TEMP
RADIO ALTITUDE
GLIDESLOPE DEVIATION
WINDSHEAR MODE
NORMAL ACCELERATION
ANGLE OF ATTACK
AIRCRAFT PARAMETERS
CAUTION/
WARNING
LOGIC
(Q) BIAS
TEMPERATURE
BIAS
GAMMA
BIAS
DYNAMIC
PRESSURE
THRESHOLD
BIAS
WINDSHEAR
CAUTION
WINDSHEAR
WARNING
OUTPUT
LOGIC
WINDSHEAR
BIAS
WINDSHEAR
OUTPUTS
GPW
INHIBIT
FILTERED SHEAR
WINDSHEAR
EXTERNAL
ENABLE
WINDSHEAR
EXTERNAL
COMMAND #1
WINDSHEAR
EXTERNAL
COMMAND #2
WINDSHEAR
ANNUNCIATION
PROGRAM WINDSHEAR
CAUTION DISABLE
PROGRAM WINDSHEAR DISABLE
PROGRAM WINDSHEAR
CAUTION WITH VOICE
FIGURE 6.5.1-1: WINDSHEAR BLOCK DIAGRAM