You don’t state what radar you use if it’s the B777 RDR 4000, the Radar is ON (Transmitting) when The System Control knob on the Radar control panel is set to L or R (dual system) or NORM (single system) and WXR is selected display on at least one Electronic Flight Display control panel while the aircraft is on the ground.
• Or the PWS Qualifiers are satisfied while the aircraft is on the ground, Engine at Take-Off Thrust Setting or both Oil Pressure Active and Transponder On.
• Or the aircraft is in the air, regardless of any other settings.
Manufacturers are required to calculate two distances; the MPEL(max permissible exposure level) boundary is determined by the greater of these two distances. The first distance is the near field/far field boundary which is the distance from the antenna that it takes for the beam to form. For the RDR-4000 this distance is 14 feet (4.27 meters). The second is the distance where the radiation level exceeds the U.S. Government standard of 10 milliwatts per square centimeter. For the RDR-4000 this distance is 11.8 feet (3.58 meters) from the antenna. In TEST mode the system transmits two 550 microsecond pulses at the beginning of the test sequence and the safe distance is 0.8 inches (2.1 centimeters) from the antenna during this period. The safe fuel distance is 3.5 feet (1.07 meters) from the antenna.
When approaching a gate, you are recommended to deselect WXR on all displays and/or select TEST on the control panel to prevent the radar from transmitting.