1. INTRODUCTION The TWR-840 system is a solid-state X-band radar. This system has a weather detection range of 300nm. Weather can be displayed on the pilot PFD, copilot PFD and the center MFD. 24 watt transmitter power: Reduces radiation hazard for personnel near the operating radar.

2. FEATURES Four color weather display. One piece receiver-transmitter-antenna. Low transmitter power (nominal 24 watts). Antenna tilt + 15 degrees

3. STANDBY (STBY) When both sides are in STBY and one side selects an operational mode, both sides will go to that operational mode. Independent radar modes may then be selected by each pilot but if either pilot selects STBY again, it will force both sides into STBY. At system power up on the ground. The radar powers up in the STBY mode. The STBY mode is automatically selected 60 seconds after air to ground transition (WOW).

4. WX MODE Detects precipitation as one of 4 colors: –Green –Yellow –Red –Magenta

5. MAP MODE Provides detailed ground returns and should be used while purposely mapping the terrain.

6. GROUND CLUTTER SUPPRESSION (GCS) Ground Clutter Suppression aids in weather identification by removing most of the ground returns. Caution: GCS should only be used to identify ground clutter. Continuous operations with the GCS feature turned on is not recommended because some precip returns may be reduced in intensity or eliminated from the display.

7. Stabilization (STAB) Antenna stabilization is used to eliminate the effects of aircraft pitch and roll to maintain a horizontal scan. It uses signals from the attitude heading system (AHRS) to maintain the selected horizontal scan. Setting the STAB function to OFF is primarily useful in the event of an attitude signal failure.

8. GAIN Normally, receiver gain should be at the 0 (norm) position. 6 other positions, 3 of increased gain and 3 for decreased gain are available. Higher settings are useful in identifying the lightest levels of precipitation and lower levels for the most intense weather targets. Each of the minus settings reduces the sensitivity by 1 color level. If a target was magenta in NORM, the same target at -3 would almost be removed. The radar should not be operated in reduced gain settings for an extended period of time.

9. TEST MODE The primary function on the TEST mode is to ensure the MFD and PFDs ability to display the necessary colors for proper system operation.