(USA) NTSB issues recommendations to the FAA and the SSA regardingtransponder use in gliders

Darryl Ramm wrote:
On Mar 31, 6:50 pm, Sarah Anderson wrote:
Greg Arnold wrote:
I see they want to require transponders in all gliders, with the
transponders always on.
Nice summary. And, in compensation we'd get the low, low transponder code of 0440

I've never heard that low codes would save power, maybe they just wouldn't ping it as
often as 1200

Sarah

Ah, that is not possible. The simple answer is all transponders seeing
an interrogation signal will reply. The SSR can interrogate the
transponder to send it's code (Mode A) or altitude (Mode C). There is
no concept of the SSR being able to "address" a transponder.

I assume what the NTSB is referring to is the duty cycle of the reply
transmission, I'm too tired right now to figure out the actual encoding,
but if 0440 has a lower duty cycle than 1200, it will save some amount
of power. How much, I don't know...

Marc