I presume he’d studied the maps, then? When I did my first few cross-country flights, the easiest navigation for places that had bodies of water was the shape of the coastline.
The shapes of Ireland near Dingle, the Irish south coast, the Bristol Channel or English Channel, Brittany, etc. would be fairly recognizable from the coastlines - distinctive island and penninsula shapes, rivers, etc. I suppose the biggest risk would be encountering low clouds over the coast. (Did he check the weather reports, unreliable as they were at the time, fo a good time to go?)
How far badly could one go with dead reckoning, with the whole of Britain and France as a target?
His best choice was hitting the south of Ireland, I wonder how easy it woud have been to navigate from up the Loire?
He had to contend with clouds, and some fog, so he sometimes climbed, trying to reach clear air. To 10000 ft, part of the way. Ice was a definite worry – guess he’d want to go lower to avoid that. So he spent time at 200 ft or less, too. Being able to see the sea helped him to guess the wind.
Say he’s off course to the south and misses the British Isles. He crosses the Bay of Biscay and comes to a north-south coast. Now what? He probably didn’t have enough map to figure where he was along the coast, and it was getting dark. Which way to Paris?
I don’t know what Lindberghs plan or preparations for that were, but obtaining a set of detailed maps of western Europe shouldn’t have been a problem at that point in time. At first glance, the Bay of Biscay seems to have a remarkably smooth line. Couple that with the compass direction the coast follows, and you should have a decent shot at figuring out where you are.
In addition, lighthouses would be very prominent and convenient markers for checking your location.
You also can estimate your latitude using the time of sunset. There would have been a difference of more than 20 minutes between Paris and Madrid, and more than 30 between Edinburgh and Paris, enough to tell whether you are far of course, and which way to turn.
My thought was that if he hit the Bay of Biscay, how easy was it to navigate to Paris across the countryside? He’d have to follow rivers, back in the day there were no big wide straight Autoroutes etc. How familiar would he have been of the various chateaus or cathedrals as landmarks?
Brittany or the English channel would have been no problem, from a few thousand feet up the coastline (and it’s compas orientation) would be pretty easy to figure out. Land’s End looks different from Ireland, the ocean/channel is on the north side of Brittany, etc.
Most likely Lindbergh had zero maps of France, aside from the portion on his transatlantic chart. After all, he didn’t have a map showing how to find Le Bourget. As it turned out, he reached the French coast near sundown, so he needed to have a good idea of where he was so he would know what compass heading pointed him to Paris so he could spot its lights in the dark. A map showing rivers wouldn’t help him at night.
I still think getting a good fix on your location at the coast would be a helpful first step. From there you could either try to fly straight in the direction of Paris, but would of course have to worry about crosswinds. You could also follow the coast, maybe until you Nantes, before heading for Paris, at the cost of taking a longer route.
Train lines could be helpful.
All that of course requires geographical knowledge, either in your head or on paper.
In his book, Lindbergh said he asked the fishermen “Which way is Ireland”. He knew once he located himself on the Irish coast, Paris would be easy, assuming clear skies.
According to an old newsreel, when word was sent to Paris that Lindbergh was spotted over England, three French planes took off to intercept him and guide him to Paris. More than that, I’m unable to discover.
Dead reckoning works, especially at altitude. Finding Ireland definitely helps. Not finding Ireland we’re talking Amelia Earhart. He knew about where he was at all times, had lots of fuel and the Atlantic is relatively easy to fly.
(probably staged)
Reporter to Ringo Starr: How do you find America?” Ringo: “Turn left at Greenland”
That presupposes a known, or at least reasonably estimated, longitude. Yes, sunset times will vary with latitude, but how do you know what time it is in your vicinity if you don’t also know your longitude? Anyway, you can ascertain latitude easily enough if the North Star is visible (at night) and, for that matter, with the noon sun if you have a visible horizon.
And of course with a decent time piece (easy enough to come by in the 1920s) he could perhaps have used local noon (if he could ascertain that while doing his level best to keep the plane steady) to estimate his longitude.
Probably the best time, really. Once over land, he didn’t need celestial navigation: he could take cues from visual landmarks. I’m not expecting he used a wrist watch to guide him to Paris, only that the best use for time I can imagine on that voyage would have been making use of the wide availability of accurate-enough timepieces (relative to the age of sail, and keeping in mind he only had to go, like, a day since his last opportunity to check the piece against a precise known time) to estimate longitude to within perhaps a hundred miles, give or take. Not much help for precision navigation, but critically important to reduce error and/or reset dead recon estimates.
That seems more plausible to me than what was originally proposed: estimating latitude based on sunset times. Because you can only do that if you already know longitude, and if you know longitude, you probably don’t need that kind of rough estimation for latitude to begin with.
Not a pilot, but did learn a thing or two (and admittedly not much more) about celestial navigation in my past life as a naval officer.
Altitude ? He was at 100 metres. He would have seen ships following the great circle. Many ships were following the great circle from Ireland or Cornwall to Newfoundland
If he landed in Paris at 10 pm on May 21 - assuming time zones (and DST) were the same as today, sunset in Paris would have been at 9:33 pm. He would have had sufficient twilight to see objects on the ground.
Sorry, but that route is going against the ocean currents. Ships would follow the Great Circle route (more or less) going to Europe, but not coming back the other way. They’d go south, to somewhere around Spain, before turning westward. Ocean currents are much more significant to ships than following a Great Circle.