Further to the posts here, I was able to obtain the ICAO report on the KLM Constellation crash at Bombay in 1949. Among other things the report mentioned the aircraft homed over the MF beacon at Santa Cruz. Later in the report it said R/T communications on 6440Kc/s were normal....and when flying over the beacon at 7000 ft the aircraft received instructions on the course to be flown.
First of all, is an MF beacon nothing more than a present day NDB - or is it something else? If so, what indications in the cockpit show the pilot is tracking towards and finally over the MF beacon. I thought all NDB's were in the medium frequency (MF?) range.
In 1949, is true to say the ATC at Bombay used only HF for comms to aircraft in the circuit area or on an instrument let down? - if so would that have been voice or Morse code? Apparently the radio operator kept a log of comms so presumably that meant translating the morse to written.