B737 Weather Radar Panel

Weather Radar Panel
P8 AFT ELECTRONICS

MODE SELECTOR

  • MAP – Displays full coverage ground map.
  • AUTO – Automatic weather presentation mode provides display of:
    • Windshear out to 5 nm,
    • Turbulence out to 60 nm,
    • Weather out to 320 nm.
    • Secondary weather returns are shown with black stripes through them.
    • Hazard Displays for lightning, hail, and Rain Echo Attenuation Compensation Technique (REACT) indications will also be shown.
  • MAN – Manual constant altitude (Weather Analysis) mode. The altitude slice defaults to current altitude upon MAN selection.

Note: In both AUTO and MAN mode of operation, the weather radar automatically increases the gain as the aircraft passes into the freezing layer to help compensate for the decrease in radar reflectivity in this area.

MANUAL ALTITUDE CONTROL

  • ALT – Controls weather analysis altitude from 0 to 60,000 ft. MSL in increments of 1000 ft.
    • Selected altitude is shown on the Electronic Flight Display.
    • Active when MAN mode is selected.

GAIN CONTROL

  • CAL – Rotate to the CAL position for automatic gain control. The CAL position results in a calibrated map or weather radar display. Gain control does not affect turbulence or windshear.
  • Manual – Rotating the knob out of CAL varies gain between MIN and MAX. VAR is shown on the display, indicating that the gain has been changed from the calibrated position.
  • MIN – Position reduces gain approximately 16 dBz below the CAL setting. Rotating the selector toward MIN reduces precipitation intensity thresholds, requiring greater intensity precipitation levels to display in red.
  • MAX – Position increases gain 10 dBz over the CAL setting. Rotating the selector toward MAX increases precipitation intensity thresholds, allowing lesser intensity precipitation levels to display in red. MAX gain should only be used at cruise altitudes to help see less reflective frozen storm tops.

Note: The GAIN knob can also be used to temporarily suppress the display of Hazard Icons and Turbulence Indications by moving the GAIN knob out of the CAL position.

SYSTEM CONTROL

  • Rotate – Selects left or right radar system. When changing the selection, display of weather data may be slightly delayed. This is due to refreshing the radar memory buffer.

Note: When WXR is not selected on the display system, no radar display is shown. While in the air, or on the ground when the radar has been auto-activated (engine throttles at a take-off position setting), the radar will nevertheless continue to operate, constantly updating the 3D memory so that current radar data is immediately available whenever WXR is selected.

Note: Automatic Windshear Activation – The windshear mode will automatically be turned on under the following specific aircraft conditions:

  • In the air below 1800 ft. AGL, or
  • On the ground with the engine throttles at a take-off position setting.

See FCOM for Predictive Windshear (PWS) Detection explanation.

  • TEST – With WXR selected on at least one EFIS Control Panel, places radar system in test mode.
    • When selecting TEST, weather radar panel lighting increases to full bright, dims, then returns to the brightness setting selected prior to selecting TEST.

Note: While on the ground, the system test will also exercise the windshear aural and visual alerts shortly after being selected. If the system control is placed in TEST while in flight:

  • The display will show the test pattern, but no windshear aural or visual alerts will be annunciated.
  • If a windshear event is detected while in the test mode, the display will switch to weather with the windshear icon overlaid, and warning or caution annunciations will be triggered, as appropriate.

No fault indications shown after completion of the test sequence indicates full radar system operation is available.