FAAM NON-CORE - RDR-4B Navigation Weather X-band Radar


weather_radarBy way of background, the Honeywell RDR-4B is a Doppler weather radar system, which also provides a predictive windshear facility during take-off and approach phases of flight. The weather radar provides visual display of weather patterns, terrain and windshear cautions, and visual and aural alert of windshear warnings. The range, tilt and gain settings for the display can also be set.


The weather radar system has been extended beyond the basic flight deck installation to include the ability of mission scientists to display weather radar data in the cabin different from that displayed to the pilots. Associated with this is a control transfer facility, between flight deck and cabin.

The pilots and the mission scientists displays are interleave, with on sweep of the scanner updating the cabin display, and the alternate sweep updating the pilot's display. Hence the update rate of both screens is halved in this mode.


The data is recorded on the JIF rack using a Ballard Technology interface card (LP708-1). The ARINC708 Data word is 1600 bits long. The 64-bit header contains information about the actual status of the weather radar (e.g. gain, tilt, range,...). The remaining bits contain the 512 data 3-bit data words.

The weather radar data are streamed at a rate of 190 Hz and are logged on a laptop at the Mission Scientist 3 position using the API supplied by Ballard Technology.


The table below lists the color codes and the related precipitation rates.

CodeColourDescriptionRainfall Rate
0 Black Very light or no precipitation [<Z2] < 0.7 mm/hr
1 Green Light precipitation [Z2 to Z3] 0.7 - 4 mm/hr
2 Yellow Moderate precipitation [Z3 to Z4] 4 - 12 mm/hr
3 Red Heavy precipitation [Z4 to Z5] > 12 mm/hr
4 Magenta Very heavy precipitation [> Z5]  
5 none not in use  
6 none Medium turbulence  
7 none Heavy turbulence  


FAAM provides the data in netCDF-format on request.



Further Details

Contact Axel Wellpott , FAAM

Additional information