Goodbye LORAN-C, its been a great journey

[Troy Scott]

I'm amazed that LORAN lasted as long as it did. The government was trying to shut it down over 10 years ago (maybe longer?). I remember flying around in the Cascade Mountains back in about 1990 and having to be careful to avoid the long wire LORAN transmission antennas. I had a FOSTER LORAN in a Bonanza back then. It was accurate enough for non-precision approaches, but as I recall, the processor was DREADFULLY slow. Once, in an emergency I called up the "nearest airport" feature, only to WAIT, while the damn thing thought about it for awhile...... These days my iPhone does a better job of navigating
Times change!

[Neil Gordon]

I have heard the "repeatability" of LORAN and its ability to bring you back to the same spot many time but never really understood what that meant or how a system that is significantly less accurate 400 meters vs. 10? meters could be more accurate in returning to the same spot. Would it be the same spot 400 meters off?

LORAN makes the same mistake each time. Think of a ruler that's marked 12 times but is only eleven inches long. Measure anything you like 100 times and you'll get exactly the same wrong answer each time.

It was great for navigating back to a place you'd been before; less viable for navigating new narrow channels in the dark.

[Troy Scott]

Neil wrote
"LORAN makes the same mistake each time. Think of a ruler that's marked 12 times but is only eleven inches long. Measure anything you like 100 times and you'll get exactly the same wrong answer each time.

It was great for navigating back to a place you'd been before; less viable for navigating new narrow channels in the dark."
(end quote)

To add to that, I think that's why, at one time LORAN was usable an an aid to approaches. The approach was based on what the actual signal was on the ground at the arrival point and of course points along the way. It did not matter what the PREDICTED numbers SHOULD be at the point in question. What mattered was that someone had actually been there and measured the numbers actually being received at the exact point in question. Armed with this information, anyone else could find the same spot. A problem, as I recall, was that atmospheric phenomena would occasionally affect even the measured signals, so in some cases monitoring equipment was in place at the goal. This equipment would broadcast the corrected and current information to the folks trying to get to the point in question. I think this same approach has been used with other electronic navigation methods, including GPS. The monitoring equipment is not a HOMING beacon, but rather part of a system for adding precision to the primary means of navigation.