The baseline RDR-4000 automates operation of the radar, and scans and stores a three-dimensional database of weather ahead of the aircraft from the ground to 60,000-ft. altitude, out to 320-nm range. The system automatically removes ground clutter from radar returns, using the terrain database from Honeywell's enhanced ground proximity warning system, and stores the weather data in a volumetric buffer.
In automatic mode, the radar displays weather along the flight path. Primary weather, within 4,000 ft. above and below the aircraft's altitude, is displayed in solid colors. Secondary weather, at higher or lower altitudes, is shown cross-hatched, to make the crew aware of storms that could affect the flight if they climb or descend.
In a conventional radar, a crew will probe the weather ahead by changing the radar-antenna tilt angle to look up and down to see whether it is possible to fly over or under approaching storm cells. With the RDR-4000, in manual mode, the pilot can select an altitude and see a horizontal slice through the volumetric buffer.
The software enhancements being introduced add the ability to predict the presence of hail or lightning in weather cells based on their radar reflectivity and to superimpose warning icons on the radar display. The density of icons on the screen is an indication of the likely intensity of hail or lightning in a storm.
The upgrade also adds rain echo attenuation compensation technology (React), which displays magenta “keep out” arcs behind intense storm cells, indicating where weather data in the radar shadow may not be reliable because the returns are outside a calibrated range. React has been a feature of Honeywell's business-aircraft radars since the 1980s, says Katwa, and the company is working on a version of the enhanced InuVue radar for business aviation.
Turbulence-detection range is extended by lengthening individual pulses within the pulse trains transmitted by the radar. This increases the radar power on target and extends range. And, as the Convair enters a limb of the storm towering to our starboard so the television news crew on board can film us bouncing around, I can personally vouch—this radar detects turbulence.