Warning Systems - Windshear

Windshear Alerts

As installed
Windshear alerts are available during takeoff, approach and landing. GPWS provides a warning when the airplane is in a windshear.

Windshear time critical warnings are accompanied by master WARNING light illumination, WINDSHEAR light illumination and voice aural alerts.

Windshear cautions are accompanied by a voice aural alert.

If illuminated, pushing a master warning/caution reset switch resets the master WARNING lights but does not deactivate the windshear warning.

Windshear alerts are prioritised based on the level of hazard and the required flight crew reaction time.

Predictive windshear alerts are inhibited by an actual windshear warning (airplane in windshear), look-ahead terrain alerts, or Radio Altitude based alerts.

Windshear Warning Indications (Airplane in Windshear)

Aural Alert	Visual Alert	Description
Two-tone siren followed by WINDSHEAR	Red WINDSHEAR on both ADIs Master WARNING lights WINDSHEAR light	Excessive windshear at the current airplane position detected by GPWS. Enabled below 1,500 feet Radio Altitude. GPWS Windshear detection begins at rotation.

Predictive Windshear Alerts

As installed
Weather radar provides alerts for excessive windshear ahead of the airplane. These are “predictive windshear alerts” and are annunciated on the HSI. The weather radar uses radar imaging to detect disturbed air prior to entering a windshear.

Note: The weather radar provides windshear alerts for windshear events containing some level of moisture or particulate matter.

Note: The weather radar detects microbursts and other windshears with similar characteristics. The weather radar does not provide alerting for all types of windshear. The flight crew must continue to rely on traditional windshear avoidance methods.

Note: The automatic function of the GPWS provides “pop-up” displays for predictive windshear and terrain. If neither pilot has weather radar on, and a predictive windshear caution or warning occurs, the weather display and predictive windshear symbol automatically show on the HSI. If neither pilot has terrain display on, and a look-ahead terrain caution or warning occurs, the terrain display will automatically show on the HSI.

Predictive Windshear Alert Indications

Predictive Windshear Display and Annunciation

Predictive Windshear Symbol
When displayed (red and black) - predictive windshear alert active. Shows windshear location and approximate geometric size (width and depth). Symbols, radials and weather radar returns automatically show when:

• predictive windshear alert occurs and
• neither pilot has WXR display selected and
• in expanded VOR, APP, MAP and CTR MAP modes.

When terrain display active, weather radar display replaces terrain display.

Predictive Windshear Symbol Radials
Displayed (amber) - predictive windshear alert active. Extend from predictive windshear symbol to help identify location of windshear event.

The weather radar automatically begins scanning for windshear when:

• Thrust levers set for takeoff or
• In flight below 2,300 feet Radio Altitude (predictive windshear alerts are issued below 1,200 feet Radio Altitude).

Alerts are available approximately 12 seconds after the weather radar begins scanning for windshear. Predictive windshear alerts can be enabled prior to takeoff by pushing the EFIS control panel WXR switch.

If windshear is not detected, weather radar returns show only after pushing the EFIS control panel WXR switch.

Predictive Windshear Inhibits

During takeoff and landing, new predictive windshear caution alerts are inhibited between 80 knots and 400 feet Radio Altitude, and new warning alerts between 100 knots and 50 feet Radio Altitude. These inhibits do not remove existing predictive windshear alerts.

Predictive windshear alerts are also inhibited by an actual windshear warning, look-ahead terrain alerts or Radio Altitude based alerts.

TCAS