Garmin GDU 37X Pilot's Manual page 142

Hazard Avoidance
When a FIS-B weather product is active on a map, the age of the data is displayed
on the screen in the lower left corner of the display. The age of the product is based
on the time difference between when the data was assembled on the ground and the
current GPS time. Weather products are refreshed at specific intervals (see Refresh
Rate in the table below).
If, for any reason, a weather product is not refreshed within the Expiration Time
intervals (see table), the data is considered expired and is removed from the display.
This ensures that the displayed data is consistent with FIS-B broadcast data. If more
than half of the expiration time has elapsed, the color of the product age displayed
changes to yellow. The system displays dashes instead of a product age when a
product has expired. If a weather product is not available or has not been received,
the system displays 'N/A' instead of a product age.
The table below shows the FIS-B weather expiration time and the refresh rate. The
broadcast interval represents the interval at which FIS-B GBTs broadcast new signals
that may or may not contain new weather data. It does not represent the rate at which
weather data is updated or new content is received by the GDL 39.
FIS-B Products
NEXRAD Composite
Reflectivity (CONUS)
NEXRAD Composite
Reflectivity (Regional)
METAR
TAF
AIRMET
SIGMET
124
Expiration
Time
~5 minutes precipitation
60 minutes
60 minutes
1 minute (where available),
8 hours
12 hours
12 hours
As Available, then at 15
12 hours
minute intervals for 1 hour
Garmin GDU 37X Pilot's Guide
™
Update Interval
(Minutes)
mode
10 minutes for clear air
As Available
As Available otherwise
8 hours
As Available
Broadcast
Interval
(Minutes)
15
2.5
5
10
5
5
190-01054-00 Rev. E