BendixKing KSN 770 - Pilots Guide - Manual (Page 201)

KSN 765/770 Integrated Communication Navigation Display
D200802000009
REV 2 Jun 2014 10-11
Datalink Weather View
Honeywell International Inc. Do not copy without express permission of Honeywell.
CAUTION
NEXRAD WEATHER IMAGES COULD BE AS MUCH AS
20 MINUTES OLDER THAN ACTUAL WEATHER CONDITIONS.
THE XM PRODUCT AGES BOX ASSOCIATED WITH THE
NEXRAD DISPLAY DATA INDICATES THE TIME IN MINUTES
SINCE THE IMAGE WAS RECEIVED BY THE SYSTEM (NOT
WHEN IT WAS CREATED OR SENT BY XM WEATHER). THIS
DELAY SHOULD BE CONSIDERED WHEN USING NEXRAD
IMAGERY, AS THE MOVEMENT AND INTENSITY OF THE
WEATHER COULD ADVERSELY AFFECT SAFETY OF FLIGHT.
The NEXRAD radar also has the following limitations:
D
Although reflectivity echoes are possible up to 248 NM, the
interpretation of the data does not work beyond 186 NM. After which
only the general shape of the storms can be made out.
D
NEXRAD is unable to differentiate between types of precipitation.
D
The radar beam is oriented 5 degrees above the horizon. As a result,
the farther from the antenna, the higher the area scanned by the
beam. This translates to limited low storm detection farther from the
individual radar location. Conversely, there is limited high altitude
storm detection directly above the radar location.
D
The image that is shown on the cockpit display is a collage of radar
images from multiple ground radar sites. When the NEXRAD
display in the cockpit is updated, it may or may not contain new
information from each ground site.
D
Weather conditions depicted on the mosaic image will always be
older than the time indicated on the display. By the time radar
images are captured and processed by the ground radar sites and
then transmitted to the aircraft, the image on the cockpit display may
exceed the time monitor indication by as much as 20 minutes. This
delay in information dissemination should be considered when using
NEXRAD imagery for weather avoidance as the movement and
intensity of the weather could affect the safety of the flight.