I'm confused. Selcal or SOCAL, ARINC or MWARA, LDOC or ATC?
<<ARINC provide a service around the mainland US where aircraft can contact their operations base via an HF radio link and then a phone call to their company operations base - nothing to do with Air Traffic Control at all.
You are conflating two different services ,both of which are operated by ARINC.
ARINC offers LDOC service to various airlines to allow them to talk to their aircraft in flight via an HF frequency.
ATC instructions are not passed on LDOC frequencies.
ARINC operates the HF MWARA land based transmitters in the US.
>>>>FAA ATC cotrollersl do NOT directly control or talk to aircraft on HF.<<<<
The operators you hear on MWARA frequencies originating in the US are ARINC employees.
FAA ATC controllers send data and flight instructions to the ARINC operators at New York Radio or SFO
The ARINC operators then relay FAA ATC instructions, to the aircraft in flight, contacting the aircraft on their assigned enroute HF MWARA frequencies.
ARINC operators also relay any ATC questions from the aircraft to the FAA ATC.
<MWARA is the "Major World Air Route Area " system where ATC control en route aircraft by HF radio and hand them over to other controllers when they reach the boundary. >
SEE ABOVE.
In the US ATC controllers do not talk directly to aircraft on HF MWARA frequencies.
FAA ATC controllers do talk directly to aircraft on VHF, but not on HF.
The only exception to this policy that I know of is at Barrow,Alaska (PABR).
There the FSS has an HF setup, separate from the ARINC HF station.
(FSS are FAA offices for filing flight plans, getting weather reports, etc, but FSS operators are NOT flight controllers, nor do thay issue any in flight navigational instructions to aircraft.)
<<Selcal is a system where the ATC controller can alert the aircraft flight crew that he want to talk to them without having their HF radio hissing in their ears all the time.>>
Think of SelCal (SELective CALling) as being similar to the tones used to alert fire departments.
The firefighters don't need to listen to dead air all the time
They only need to listen when thay are being directly called.
SELCAL alerts you to pay attention to the radio. "LISTEN UP! Someone is calling you!"
<<ARINC is a company owned by Collins who provide the equipment and operators for ARINC>><<
<<but MWARA controllers are employed by the FAA I believe.>>
In North America ATC controllers DO NOT talk on HF.
in the US they are ARINC employees, in Canada they are mployed by NavCanada.
<<There is no LDOC in New Zealand,>>
Why not?
It would make much more sense to have on organization to provide all the technical expertise to operate LDOC rather than have multiple xmtrs with rather dubious maintenance regimes.
the major international companies have direct HF communications into their operations offices via discrete frequencies..
Here's a nice big chart that tells you everything..... it's a wee bit out of date but not much has changed....
http://www.liveatc.net/downloads/hfaero.jpg