Mostly correct but---

Per AIM Ch 3, sect 2, #1 f 2 mandatory Safety Alert provided to ALL
aircraft, conflict Mode C intruder alert (I presume this applies to
transponder equipped aircraft only)

and

3-2-3 Class B airspace---e. ATC clearance and separation provided to VFR
aircraft
and 3-2-4 Class C airspace ----e aircraft separation provided to VFR
aircraft.

So---if a plane is transponder equipped ATC is required to give a traffic
alert if the controller detects an unsafe proximity. The warning would be
given on the "local" ARTCC frequency, I guess.

--
Hartley Falbaum
"Bubba" wrote in message
om...
In the US, ATC is only responsible for providing separation services
between IFR aircraft, not IFR from VFR. They will call out VFR aircraft
time permitting. A glider pilot with a transponder might have the false
impression that someone is providing separation services for them. This
could happen as work load and time permit for ATC. So to sum is up:

1) ATC is not required to inform a VFR or IFR pilot of other VFR traffic.
2) It is the responsibility of both VFR and IFR pilots to avoid VFR
traffic.

Even if ATC calls out your position while thermaling, an aircraft
traveling 250 kts might only get a glimpse of you ever mile while you
circle (assuming you are visible when perpendicular to their flight path
twice in a turn). With TCAS, a glider pilot has better chance of
detecting approaching aircraft both VFR and IFR that are squawking codes
and see / avoid them first.