If the aircraft is above 29,000 feet, be cautious of any target return that gets to 30 NM or closer. This is likely a thunderstorm that has a top high enough that the aircraft cannot fly over it safely.

If the aircraft altitude is 15,000 feet or lower, set the displayed range to

60 NM. Closely monitor anything that enters the display.

Also, after setting up the antenna tilt angle as described previously, ground returns can be monitored for possible threats. The relationship between antenna tilt angle, altitude, and distance is one degree of tilt equals 100 feet of altitude for every one nautical mile.

Foreword

 

System

Sec 1

PFD

Sec 2

 

 

 

 

 

 

 

4000

(feet)

 

 

 

 

 

 

 

 

 

 

 

 

 

3000

 

Change in Antenna Tilt

 

Beam

 

 

 

 

2000

+4°

 

 

 

 

+3°

 

 

 

1000

Radar

+2°

 

 

 

 

 

 

 

+1°

 

 

 

0

 

 

 

 

of

-1°

 

 

 

 

 

 

 

 

1000

Change

-2°

 

 

 

 

-3°

 

 

 

 

 

-4°

 

 

 

 

2000

 

 

 

 

 

 

 

 

 

3000

Vertical

 

 

 

 

 

 

 

 

10 nm

 

 

 

4000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4-72 Vertical Change in Radar Beam per Nautical Mile

Therefore, with the antenna tilt set so that the bottom of the beam is four degrees below parallel with the ground, a target return at 10 NM is approximately 4,000 feet below the aircraft; at 20 NM, 8,000 feet; at 50 NM, 20,000 feet. In other words, at this tilt setting, a ground return (such as a mountain peak) being displayed at 10 NM would have a maximum distance below the aircraft of 4,000 feet. If that ground target return moves to 5 NM, maximum distance below the aircraft will be 2,000 feet.

This setup will provide a good starting point for practical use of the GWX 68. There are many other factors to consider in order to become proficient at using weather radar in all situations.

4.10.5Weather Mapping and Interpretation

4.10.5.1Weather display Interpretation

When evaluating various target returns on the weather radar display, the colors denote approximate rainfall intensity and rates as shown in the table below.

Sec 3 MFD

 

Sec 4 Hazard Avoidance

Features

Additional

Sec 5

& Alerts

Annun.

Sec 6

Symbols

Sec 7

 

Glossary

Sec 8

 

Appendix A

 

 

Index

Appendix

 

 

B

 

190-00601-02 Rev. E

Garmin G600 Pilot’s Guide

4-87

Page 247
Image 247
Garmin G600 manual Weather Mapping and Interpretation, Weather display Interpretation