Fis-B Weather (Optional); Nexrad Abnormalities; Nexrad Limitations - Garmin G500H Pilot's Manual

4.9

FIS-B Weather (Optional)

WSR-88D weather surveillance radar or NEXRAD (NEXt generation RADar) is
a Doppler radar system that has greatly improved the detection of meteorological
events such as thunderstorms, tornadoes, and hurricanes. An extensive network
of NEXRAD stations provides almost complete radar coverage of the continental
United States, Alaska, and Hawaii. The unobstructed range of each NEXRAD is
124 nautical miles. The GDL 88H receives the FIS-B information and sends it
to the GDU 620.
NOTE: The GDL 88H will send all FIS-B weather and NOTAM/TFR
information that it receives. There may be more information available than
is received by the GDL 88H. This can lead to the GDL88, and subsequently
the 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 Abnormalities

There 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-line
4.9.2

NEXRAD Limitations

Certain limitations exist regarding the NEXRAD radar displays. Some, but
not 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. The
CONUS NEXRAD "pixels" are 7.5 minutes (7.5 nautical miles = 13.89
km) wide by 5 minutes (5 nautical miles = 9.26 km) wide. Above 60
degrees of latitude the Regional NEXRAD "pixels" are 3 minutes/nautical
miles. CONUS NEXRAD is not available above 60 degrees of latitude.
The intensity level reflected by the pixel will be the highest level sampled
within the area covered by each pixel.
NOTE: Where it is noted that NOTAM data is available, it is possible only
a subset of the data is available and that more NOTAM reports may arrive
in future updates. Updates occur approximately every ten minutes.
190-01150-02 Rev. J Garmin G500H Pilot's Guide
4-107