T
RAINING
M
ANUAL
–
L
ANCAIR
IV/IVP
These handy devices not only show precipitation detected by the nation’s ground
based NEXRAD weather radar system but they also can give you METARS and
TAFs for selected destination airports, depict SIGMETs and AIRMETs, show
winds aloft, freezing levels, etc.
As with any instrument you must be aware of Datalink’s limitations in order to use
it properly in the cockpit. Datalink is a great device for making strategic decisions
about weather flying. Shall we fly through Tennessee or Kentucky on our way to
Norfolk, Virginia? Datalink is not a good tool to navigate through a line of
embedded thunderstorms in IMC conditions. The reason for this is the delay in
collecting, analyzing, correcting and posting the data stream to the satellite and
then the download and processing on the aircraft end. All of this takes time and
meanwhile the cell you are trying to stay out of may be moving at 50 knots right
into your path—so you have to give your self a wide berth if you are IMC. The
other issues to consider is that the information posted on the datalink may not be
accurate for the altitude you are flying. The area you are in may be showing light
green precipitation but you may not be getting any precipitation or may be getting
worse precip.
Another limitation that datalink has is there is limited coverage outside of the
Continental United States as well as limited NEXRAD coverage in mountain
states. Two Lancair accidents in recent years involved pilots who may have
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2007
LOBO
May
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without
permission.