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
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..

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.