Garmin GTN 750 Pilot's Guide - Page 257

12.1.5.2 NEXRAD Limitations NEXRAD radar images may have certain limitations: • NEXRAD base reflectivity does not provide sufficient information to determine cloud layers or precipitation characteristics. For example, it is not possible to distinguish between wet snow, wet hail, and rain. Foreword Getting Started Audio & Xpdr Ctrl • NEXRAD base reflectivity is sampled at the minimum antenna elevation Com/Nav angle. An individual NEXRAD site cannot depict high altitude storms at close ranges. It has no information about storms directly over the site. FPL • Each square block on the display represents an area of four square kilometers (2.15 NM). The intensity level reflected by each square Direct-To represents the highest level of NEXRAD data sampled within the area. Proc Charts Block Area Is 4 km2 (2.15 NM2) Wpt Info Map Traffic Block Area Is 4 km2 (2.15 NM2) Terrain Weather Figure 12-9 NEXRAD Data Blocks Nearest The following may cause abnormalities in displayed NEXRAD radar images: • Ground clutter Music • Strobes and spurious radar data Utilities • Sun strobes (when the radar antenna points directly at the sun) System • Interference from buildings or mountains, which may cause shadows • Metallic dust from military aircraft, which can cause alterations in radar Messages scans Symbols Appendix 190-01007-03 Rev. B Garmin GTN 725/750 Pilot's Guide 12-11 Index