Selcal in the '70s and '80s
romeocharlie:
You're not a knob; your recollections are quite correct. Sit down children while you receive a history lesson from an old codger long before the days of "Brisbane International".
Prior to '85 SELCAL facilities were only available on the international HF workstations located within the Flight Service Centres at Sydney, Perth and Darwin (this is in the days before FS was amalgamated with ATC). The Selcal networks were the SP6 network (South Pacific), the SEA3 network (South East Asia) and the INO5 network (Indian Ocean).
The Sydney Flight Service Centre was equipped with SP6 and SEA3 frequencies, the Perth Flight Service Centre had SEA3 and INO5 frequencies while the Darwin FSC only had SEA3 frequencies.
Sydney used SP6 for all aircraft travelling to NZ, Honolulu, Tahiti and Nadi and SEA3 for all aircraft operating within trans-continental control areas (R576 etc) but outside VHF range of ATC. Perth used INO5 for all aircraft travelling to Columbo, Bombay, Cocos, Mauritius and South Africa and SEA3 for international aircraft travelling to Asia as well as all domestic aircraft operating within the transcontinenal control areas (TCTAs). Darwin FSC operated a similar concept.
It must be remembered that ATC VHF coverage was very limited over continental Australia in the '70s and '80s, not like now. For example, Sydney ATC VHF coverage only extended to Parkes, requiring flights from Sydney to Alice Springs having to be transferred to HF until 150nm AS before they were then transferred to Alice Tower on VHF. Aircraft overlying AS for Asia were virtually left on HF for the rest of their flights until they established VHF contact with Bali or Jakarta. Perth ATC coverage to the east only extended to about Esperance requiring aircraft to be transferred to HF before crossing the Bight (and vice versa). ATC VHF coverage to the north of Perth ceased at about Ballidu and Carnarvon. Brisbane ATC VHF coverage to the west ceased at Taroom. I can't recall the extent of ATC VHF coverage to the south of Darwin.
Therefore, many domestic airlines (mainly B727s) travelling in TCTAs to Darwin, Alice Springs, Mt Isa or Perth (over the Bight) were often transferred to SEA3 international frequencies even though they were actually domestic flights. The main reason for this is that the FSOs manning the international HF workstations in Sydney, Perth and Darwin had direct coordination links with the ATC units responsible for the TCTAs, whereas some of the domestic FS HF units didn't. This resulted in more efficient processing of level change or diversion requests from aircraft operating in the TCTAs.
Therefore, it was not unusual in those days for Ansett and TAA B727 pilots to be transferred to a Selcal watch on international HF frequencies when operating within TCTAs but outside of ATC VHF coverage.
Herewith endeth the history lesson; now I can go back to reminiscing about the good old days when aviation was actually fun (I know you pilots hated all the crackle and pops but I loved it! Probably explains why my wife thinks I am not quite right in the head)