"Andrew" wrote in message

ATC says "radar contact, 20 miles south of XYZ, proceed on course". Do
you acknowledge this transmission? How about when ATC says "altimeter
setting 2992" on your first contact after a handoff? Does this require
acknowledgement?

Yes.

In the past, I've acknowledged such things if the controller was not
busy. But I've heard all kinds. Some people read back the altimeter
setting. I've even heard people reading back the "radar contact"
message. I feel that this is a waste of bandwidth. However, I don't
know what ATC prefers. Do they want read back for everything, or should
we shut up as much as possible?

Learn to get a quick feel for how busy they are. NYC Class B is insanely
busy and ATC there can practically tell what you mean if all you do is
grunt. Try to anticipate how important your read back will be to them.
Traffic confirmation, exact traffic confirmation, helps them immensely and
is worth the time to let them know if you're really sure you have the
traffic they're talking about. Things like radar contact and altimeter
setting only require your abbreviated call sign (assuming that's how they ID
you) as a response. Xponder code should be read back if you have the
slightest doubt you you've heard it correctly. If things are slow, read
back everything. If you can arrange it, pay a visit to a tower or ATC
facility. It's worth the time.

moo