RAF Navigation
Slightly off thread, but I was an RAF navigator in the 60's, flying in Shackleton's out of RAF Changi. We carried out Search and Rescue duties in Gan, and so flew long sea legs across the Indian Ocean. Navigation was by mechanical airplot and single position line mpp's using a sunshot. Occasionally able to get a fix using a merpass. If the NDB at Gan was u/s, it was common practice to use " find the island technique", obviously track accuracy was not as stringent as the North Atlantic.