4-107190-01150-02 Rev. J Garmin G500H Pilot’s GuideForewordSec 1SystemSec 2PFDSec 3MFDSec 4HazardAvoidanceSec 5AdditionalFeaturesSec 6Annun.& AlertsSec 7SymbolsSec 8Glossary Appendix AAppendix BIndex4.9 FIS-B Weather (Optional)WSR-88D weather surveillance radar or NEXRAD (NEXt generation RADar) isa Doppler radar system that has greatly improved the detection of meteorologicalevents such as thunderstorms, tornadoes, and hurricanes. An extensive networkof NEXRAD stations provides almost complete radar coverage of the continentalUnited States, Alaska, and Hawaii. The unobstructed range of each NEXRAD is124 nautical miles. The GDL 88H receives the FIS-B information and sends itto the GDU 620.NOTE: The GDL 88H will send all FIS-B weather and NOTAM/TFRinformation that it receives. There may be more information available thanis received by the GDL 88H. This can lead to the GDL88, and subsequentlythe GDU620, displaying the status of the FIS-B data as “received” and“current” even though some of the data for the region is missing.4.9.1 NEXRAD AbnormalitiesThere are possible abnormalities regarding displayed NEXRAD images. Some,but not all, causes of abnormal displayed information include:• Ground Clutter• Strobes and spurious radar data• Sun strobes, when the radar antenna points directly at the sun• Military aircraft deploy metallic dust which can cause alterations in radar scans• Interference from buildings or mountains, which may cause shadows• Scheduled maintenance may put a radar off-line4.9.2 NEXRAD LimitationsCertain limitations exist regarding the NEXRAD radar displays. Some, butnot all, are listed for the user’s awareness:• The Regional NEXRAD “pixels” are 1.5 minutes (1.5 nautical miles= 2.78 km) wide by 1 minute (1 nautical miles = 1.852 km) tall. TheCONUS NEXRAD “pixels” are 7.5 minutes (7.5 nautical miles = 13.89km) wide by 5 minutes (5 nautical miles = 9.26 km) wide. Above 60degrees of latitude the Regional NEXRAD “pixels” are 3 minutes/nauticalmiles. CONUS NEXRAD is not available above 60 degrees of latitude.The intensity level reflected by the pixel will be the highest level sampledwithin the area covered by each pixel.NOTE: Where it is noted that NOTAM data is available, it is possible onlya subset of the data is available and that more NOTAM reports may arrivein future updates. Updates occur approximately every ten minutes.
