Robert M. Gary wrote:
I assume you are saying that your TIS goes into "coast mode" and stops
updating for a period of time.

No. The box recognizes that it's being interrogated by the radar and
it responds with altitude data. It's programmed to display when the
mode S data does not contain TIS. That's the issue. TIS information
has been unavailable for as long as months at a time in Seattle. It
has been my experience that it is "rarely" available currently. I
would be interested to know if this is isolated to the NW or if the
entire country experiences this?

I would love to have ADS-B (the current name appears to be TIS-2). It
cost us $1000 to put TIS in the plane since we had the 430 and were
going to purchase a new transponder anyway. The Feds are still
thrashing around with the specs for the new TIS but currently politics
seem to be pushing to use the current spectrum which is too congested
to handle all the data. Sad but true.

A flight in the Seattle area will routinely put you in conflict with
dozens of other aircraft. We have congested airspace and mountains
that put a lot of VFR traffic in a small space. If TIS was only useful
for a year or two I'd consider it worthwhile. The Feds have indicated
that deployment of ADS-B in our area is a decade away.

Thanks,
Dave