"skym" wrote in message
ups.com...
It is my understanding that 7700 is what we are supposed to dial into
the xpdr when we declare an emergency. I was in controlled airspace.
Does that make a difference?

Yes - it lights you up distinctly (a different colour, I believe) on the
radar screen. So although the controller would see you no matter what code
you were transmitting, if you switch to an emergency code (7700, 7600, 7500,
etc) the equipment makes you more prominent and so lightens his workload a
little.

D.