This requirement that planes be within a certain distance of land at all times is a myth. While some flight plans are adjusted slightly for safety, there are absolutely long haul routes that just blaze right across a wide-open ocean.
Not flying long distance does not mean staying home. Unless you live on a 500m radius island in the middle of an ocean with next land mass thousands of kilometers away.
There is more flexibility on routes over the middle of a trip than near the departure or arrival constraint. Flight over large bodies of water tends to be away from the arrival or departure airport.
Going 100 miles out of your way for weather at a point that's 100 miles from the airport is a big diversion. Going 100 miles laterally out of your way at the midpoint of a 2500nm trip is about an 8 nm deviation (4nm out and 4nm back).
Single engine aircraft with a range of around 800 miles are regularly ferried across the Atlantic. Now, I'm not for a minute suggesting that this is an everyday pleasure flight, it's something which takes planning, preparation and additional equipment. However, all I'm pointing out is that range would be the least of your problems if any of the claims prove true.
As long as your destination is out across the ocean and doesn't involve flying back over the city. I suppose if it's fast enough you can go "the long way" anywhere on Earth.
To cross the Atlantic between NA and Europe you need to be able to travel 138 minutes from an airport, although for almost the entire area it’s 120 minutes.
This is accomplished by having air strips which can take massive planes like A350s at remote places which can’t justify planes of that size normally like Newfoundland, Greenland and the Azores
While these are mainly there for military and temporary emergency use, in 2001 they were used far more - with dozens of planes landing at tiny towns like Gander and St. John’s in Newfoundland, places which only really expect a single large plane to land and refuel rather than 30 with passengers to accommodate for days.
The "certain number of minutes" includes being over oceans. If you're too many minutes, you can't fly there. ("Minutes" are fairly large. I believe at least one Airbus aircraft is now at 4 hours.)
Driving is not always possible, especially when there's an ocean in the middle of the trip. In that case, spending a dozen hours in a plane is much preferable to a week or more on a ship.
Can’t you do coast-to-coast? I thought the requirement is no sonic boom over land, but you can fly out over the ocean and then turn around at Mach N. Eg SF<>NYC would be an obvious route that is worth adding some miles at the start, if you can go 3-4x quicker.
Transoceanic aircraft need lots of ETOPS time. For example the boeing 777 (twin-engine, transoceanic) has an ETOPS of 330 minutes, so it always needs to be 330 min away from an airport (which is 11 hours of flight from airport A to airport B, not taking wind into account)
Twin engine planes absolutely can cross oceans -- if you need three hours' flying distance in the worst case (ETOPS-180), then you can cross up to six hours of water between any two backup airports. North Atlantic routes have only a few hours of contiguous water between, say, Greenland and Iceland. Even the Pacific has enough small islands (e.g. Hawaii) to make something like this possible (shaded areas are outside 3-hour range):
Every year or two, people decide to fly from North America to Europe in a short range Cessna. They get the extra fuel tankage package, then hop from PEI to Greenland, Greenland to Iceland, then Iceland to.... Svalbard, or maybe somewhere in the Scotish Isles. From there it's pretty standard flight operations over local bodies of water. If a Cessna can do it, that's well within a bird's migratory travel distance.
Since it's mostly 747 and similarly large planes on intercontinental flights anyway, I doubt this is much of an issue. I wonder if there actually is anywhere in the CONUS that's more than 3 hours from at least a rural airstrip?
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