On Mon, 12 Jun 2006 06:16:21 -0700, Sam Spade
wrote:

Roger wrote:

On 9 Jun 2006 17:04:28 -0700, "Robert M. Gary"
wrote:


The 396 has some advantages and disadvantages when compared to
airborne RADAR. Starting with the good, it does not have the blind
spots you will find from time to time in airborne RADAR caused by
absorption in heavy precipitation which can hide some nasty stuff.
OTOH if you keep in mind that the display is probably 5 minutes old or
a tad more AND you have been following it you can pick your course.

All systems have their limitations, including airborne weather radar.
That is the reason that the prudent operation of airborne weather radar
requires minimim avoidance distances, depending upon altitude and
weather the outside air temp is above freezing.

The limitation you cite indeed exists but can be avoided through use of
distance-to-avoid parameters and not pushing the envelope to get the

But again in the context of the OP it takes experience to realize
these things exist.

When you see a line and particularly a bow that starts out green on
your side, then yellow and then red followed by nothing it's time to
go some where else. That is no guarantee that sever weather exists
behind that line but it's a good indicator.

Like you and others have said, being conservative, using all available
information, and education are the important items.

mission accomplished, so to speak. The EAL wind shear crash at JFK, the
Delta L-1011 wind shear crash at DFW, and the Soutern Airways DC-9 crash
in southern Georgia all happaned when penetration rather than avoidance
was attempted..

When this stuff can take the "big boys" down the smaller stuff should
be some where else entirely.


The ideal setup in high-end aircraft today is airborne radar with the
largest feasible antenna and piped in weather radar for planning
purposes. The latter doesn't work in much of the world, though, just
like the 396 won't provide weather outside the 48 states.

There are areas where it won't do that good a job inside the US
either, but for the most part it can be a very useful tool,
particularly when used in conjunction with other available
information.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com