On 3/5/2011 1:21 PM, Mike Schumann wrote:
On 3/5/2011 2:04 AM, Eric Greenwell wrote:


If you intend to operate in USA Class A airspace without a waiver, then
getting the higher altitude rated transponder makes sense. The extra
cost of the unit is small compared to the ongoing testing requirements
of your transponder, altimeter, and static system, so there is no point
in taking a chance the encoder might not be accurate enough at the high
end (30,000+?).

I am still curious about the differences between the two models, beyond
the obvious one of output power.

If you are flying above 18K in the US without a waiver, don't you need
to be on an IFR flight plan, IFR qualified and current, and in an
aircraft properly equipped and certified for IFR operation?

I'm sure you do need to be operating IFR, and I believe that would
include having the proper class of transponder (but I can't point to the
regulation that says that). That's what I meant by "getting the higher
altitude rated transponder"; i.e., not the up to 15,000' rated one.

If so, I
suspect that almost all glider operations in the US above 18K require
some form of waiver.

I believe that is true, and I also believe it's true you could use your
15,000' rated transponder without any safety impact when using a waiver
to operate over 18,000'. HOWEVER, I don't know what the regulations
require of your transponder installation when operating with a waiver in
Class A.

And, I am still curious about the differences between the two ratings
(above/below 15,000), beyond the obvious one of output power.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)