Even the Weather Radar in the G650 Is Breaking New Ground

3-D weather radar system shows pilots the shape of things to come
g650, aviation, avionics, technology
Written By J. Mac McClellan

For almost 70 years, pilots have been using radar to locate thunderstorms and heavy precipitation and to avoid the worst. But until now, using radar was like looking around a pitch-black room with a flashlight. All you could see were small glimpses of the storm where the radar beam washed over. Pilots had to adjust scan and tilt angles to see bits and pieces of storms ahead, and then mentally assemble those pieces of information to form a best guess of how bad the weather really was, and exactly where the storm cell was located.

Honeywell’s new 3-D weather radar in the Gulfstream G650 changes everything. 3-D is the first all-new technology radar in years and is the first truly “smart” system that automatically detects and analyzes many significant characteristics of the weather and presents G650 pilots with a comprehensive, unambiguous picture of turbulent or severe weather along the flight path.

All radars function by broadcasting a radio frequency signal and then listening for that signal to be reflected back. Weather radar is designed so that its signal is reflected back by bouncing off precipitation and returning those echoes to the instrument—in other words, showing the raindrops. By timing the round trip from the antenna out to the rain and then being reflected back as echoes, the system calculates the distance to the precipitation. The radar notes the direction the antenna is pointing when it receives the reflected energy to determine where the rain is relative to the aircraft and its flight path.

But it isn’t rain that concerns pilots. Aircraft routinely fly through rain with total safety and comfort. However, rain can be the signature of severe weather, which all pilots seek to avoid. And that’s the power of 3-D radar—automatically showing pilots which precipitation areas are benign rain and which areas contain turbulence, lightning and possibly wind shear.

3-D weather radar performs a multidimensional analysis of the weather ahead by scanning side-to-side like any conventional radar would to see the horizontal dimension of the storm, but the 3-D radar system also scans up and down to look at the full vertical height of the storm cell.

Severe storms have predictable rain patterns, particularly when viewed at various elevations. If radar looks only at the part of the storm near the surface, as conventional radar does, it shows pilots one picture. But higher up in the storm is where hail, lightning and severe turbulence can form, and 3-D radar continuously and automatically examines all parts of the storm.

Precipitation reflects energy back to any radar, but those same raindrops also absorb, scatter and diffuse the radar energy. Engineers call this “radar attenuation.” Because of attenuation, conventional radars can’t look very deep into a storm. But 3-D radar can trick attenuation by using a variety of transmission pulse lengths and pulse rates that can penetrate the weather to see beyond the initial area of heavy rain to show pilots the actual location of worrisome and potentially severe weather.

The terrain below an aircraft has always been a big problem for pilots trying to understand what radar is showing them. The ground, particularly hills or mountains or cities with tall buildings, bounces back a radar image that can look indistinguishable from rain in a thunderstorm. It takes a great deal of skill, and fine-tuning with radar adjustments, for pilots to discern if they are seeing ground clutter or severe weather on a conventional radar.

To solve that radar anomaly, 3-D weather radar uses Honeywell’s global terrain map—the same data that warns pilots if they are flying too low—to automatically remove all ground clutter. It “sees” a radar return, looks at its terrain data, and says, “Aha! There is a hill there so that return is terrain, not weather.” When pilots see a return on 3-D radar in the G650 they know they are looking at real weather, not ground clutter.

Until now, using radar was like looking around a pitch-black room with a flashlight. All you could see were small glimpses of the storm where the radar beam washed over.

3-D weather radar is also the most capable turbulence-detecting radar ever developed. To find areas of significant turbulence it relies on the Doppler phenomenon to locate precipitation that is moving very rapidly. The Doppler phenomenon is the apparent frequency shift of a sound or radio wave in motion. For example, we all experience the Doppler phenomenon when we hear a train horn change pitch as it passes by. The horn is actually emitting the same sound continuously, but the motion of the train, thanks to the Doppler phenomenon, alters the tone before it reaches our ears.

The same Doppler phenomenon takes place when the electronic beam from 3-D weather radar is reflected back from rain droplets that are churning inside a storm. It is the rapid and conflicting movement of air currents in a storm that creates turbulence that bounces an aircraft around. These turbulent currents propel the droplets at a quite high speed; 3-D radar’s Doppler logic detects that motion and shows pilots where turbulence is located so they can avoid the area.

As you can imagine, we are talking about very small frequency changes to make the Doppler techniques work, and a very smart computer to process those changes. Some earlier weather radar designs can find turbulence a few miles ahead, but 3-D radar can spot significant turbulence as far as 60 miles ahead of the G650. It is the first weather radar system to meet this demanding standard that was created by the Federal Aviation Administration.

On approach to land, wind can make abrupt changes in velocity and direction. This is called wind shear, and it can threaten the safety of any aircraft. 3-D radar uses the same turbulence-finding technology to detect wind shear and predict if it will be a threat.

The bottom line is that 3-D weather radar will show G650 pilots the safest and smoothest route around threatening weather. And it can help the G650 complete more trips smoothly on schedule because it eliminates the false alarms and uncertainty of conventional radar. With 3-D weather radar G650 pilots will know the safe and comfortable route to complete a flight because 3-D radar automatically and reliably shows them where not to fly.



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