The passage of time doesn't diminish the usefulness of local navigation techniques... a Mercator projection will give you a bearing to steer to arrive at your

The passage of time doesn't diminish the usefulness of local navigation techniques... a Mercator projection will give you a bearing to steer to arrive at your destination, which can be followed by eye, autopilot, etc etc. Calculating a great circle arc and plotting it, following a bearing which may only change by a degree or two but isn't constant, is an unnecessary complication on short routes. Even commercial vessels will use those old techniques if they don't need to consider the longer range effects. Error correction in the human process is always a consideration. (Not even talking about data entry errors in GPS systems, but that Malaysia - Melbourne story was Funny.)