Transponder: Mode-C or Mode-S?

John Smith wrote:
Eric Greenwell wrote:
What regulation makes it illegal for a glider to use the TT21
between
15,000 and 18,000'?

Of course it's not illegal to turn on a class 2 transponder above
15,000 feet. But with a class 2 transponder, you can't tell ATC above
15,000 feet that you're transponder equipped,

Ah you want to show us a regulation or chain of regulations that says
that? Which country are you flying in? You keep using the word legal and
illegal etc. In the USA the FARs actually do not appear to place clear
requirements in this area on the PIC. Show us the regulations please...


And just for kicks 14CFR 91.215(c) "Transponder on operation" requires a
pilot say who climbs above 15,000' with a class 2 transponder to keep
operating that transponder.

because legally, you're not. Where I fly, I pretty routinely enter
protected airspace at that altitude, and I would hardly get a
clearance without a transponder. This has been the main reason for me
to buy a transponder, so buying class 2 transponder would have been
pretty pointless.

And buying class 2 would likely have made no difference to any if that.


I don't care whether "they" would notice or not that I carry only a
class 2 transponder. The price gap of a mere $200 is far too small to
even consider to cheat.

Of course all depends on where you fly and to whom you want to sell
your glider later. So all I've wanted to say is that when you consider
to buy a class 2 transponder, be aware of the limitation.


and that's all fair but the more important thing is getting pilots in
key high traffic areas to equip and use transponders (of any class or
type)). And for most pilots in the USA it is not about clearances, it
is about avoiding an encounter with an airliner or fast jet.

Darryl

If you intend to use any smart PCAS (e.g. PowerFLARM) you want a Mode-
S, since suppressing your own transponder signal is a lot easier and
more reliable if the source is a Mode-S.
Other PCAS are also somewhat more likely to make sense of your
transmissions.
So do yourself and the World a favor and buy a Mode-S.

Ironically your decision is between buying into technology of the
fifties vs. the seventies...

Enjoy
Urs