US ATC circa 1945-50.
A very brief synopsis.
No radar, except at large terminal areas, therefore, procedural traffic separation in force.
Airways navigation by LF radio range and NDB's until about 1949, when the first few VOR's began to appear...thanks mostly to the efforts of Reed Pigman, and (later on) his company, American Flyers Airline.
A mixture of LF and VHF used for ATC communication.
All control towers had LF, and this was used extensively for pilot ATC communication.
No 'fancy' airspace structure as we have today, however there were control zones around airports with control towers.
Enroute traffic separation was mainly LF communications with the respective airline companies operational center, which then passed on the aircrafts position, ETA's (etc) to the regional CAA office, who then determined separation, and these instructions were then relayed by land line back to the respective airlines operational center, who then passed along these instructions to the airplane.
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