In the days before GPS, how did planes find their way back to their aircraft carrier, especially since the carrier would not be where it was when they took off?
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Navigation is a difficult task.
It was so difficult that some powers needed a navigator on fighter planes.
There was pen and paper navigation that often led to errors where a navigator would mark the planes track over a journey.
There was also transponder type navigation where a carrier would send out a radar pulse which was used to supply planes with bearing and distance.
It was a heck of a lot less accurate, for one. Planes would use a compass and stopwatch to estimate where they were and told where the carriers would be when they came back. If this sounds horribly janky and unreliable, it’s because it was. There are cases of pilots getting lost and disoriented and not making it back to their carriers before they ran out of fuel. Thankfully, pilots had a Commanding view of their surroundings due to being at altitude so even if they were a dozen miles off a pilot could still spot the carrier. For those that didn’t, that’s what search and rescue was for.
They knew where they were going (roughly), and knew where the carrier was supposed to be when they returned. So when the fight was over, they’d point in the direction the carrier was supposed to be relative to where they think they were, and hope for the best. Formations would spread out as far as they could, and the first to spot the carrier would radio the others.
Radio transmitters have existed as long as carrier aviation and radios-based navigation system too.
US carriers did use a system with a rotation radio transmitter tath sent a more code letter depending compass direction of the transmitter. It was a 30 degrees segment per letter and the antenna rotates twice per minute.
The carrier airplanes have receivers and by just listening to the Morse code letter they could determine in what compass direction it was located. They changed the letter in a specific direction every day so the enemy could not use it.
So a pilot could just listen to the radio and receive a Morse code H. If that letter today was for 210 to 240 degrees he would need to fly in the reciprocal direction of between 30 and 60 degrees. So fly in that compass direction you go towards the carrier.
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I would be quite surprised if modern carrier aircraft require GPS to fly back to the carrier. There has to be some backup system that can be used if the GPS system is destroyed during a war.
There _were_ scrambled homing beacons available – [the navy ZB-series of homing adapters (the rest of the system were AN/ARR, ARC-5 blah blah)](https://en.wikipedia.org/wiki/AN/ARC-5).
[Here’s a good breakdown of how they worked.](http://www.skywaves.ar88.net/Presentations/YE-ZB%20Presentation.pdf) – basically, as the homing transmitter on the carrier rotated, twice a minute, the morse letters it broadcast changed every 30 degrees. The morse letter would correspond to a compass heading that the pilot had to fly to get back to the carrier.
So as you flew, every 30 seconds your ZB receiver would blip out a morse code letter. You check your decode card for the letter and that gives you a rough 30 degree cone heading back to the boat. As you drift through those heading cones or the carrier moves the letters change and by the time they’re changing rapidly you probably have the boat or one of its escorts in sight.
But, there were other ways – some naval aircraft (torpedo bombers and the like) would have multiple crewmen, one of whom could do radio navigation, dead reckoning w/ a map and/or a crude calculator thing (like a compass crossed with a slide rule) using your heading OUT from the carrier, your speed, carrier’s heading, ITS speed etc.
Primarily, radio beacons (that is the aircraft carrier transmits a signal and the airplane had equipment that could figure out the direction of the signal, so just fly in that direction until you find the aircraft carrier.
Later, they had LORAN, which worked kind of like GPS, but without the satellites. That would let you figure your location close enough to get to the radio beacon.
I think for most of WWII, they just didn’t stray that far from land or the carrier unless they had LORAN.
After WWII they started coming out with inertial navigators which perform dead reckoning and let you figure out your position with only your starting position known.
You would typically have someone write down all the directions and speeds as you go along and then calculate your position. This does require accurate wind measurements which were often broadcasted by radio from one of the ships or nearby islands. For shorter trips of an hour or two from an aircraft carrier you could just assume the wind did not change. When you returned you would still not expect to find it directly but the fleet would often spread out a bit so you might spot a patrol aircraft, a destroyer screening the fleet or the wake of one of the ships. This was not easy work. You often needed a dedicated navigator in the airplane or at least in the formation as the task of both flying and navigating was too much. And even then pilots got lost from time to time. Even into the 70s pilots lost track of where their aircraft carrier were and had to ditch the aircraft due to a lack of fuel.
One improvement that came during WWII was the invention of directional beacon. This was first developed fully by the Germans to guide bombers to their targets. But they can be used by aircraft carriers as well to help their pilots find the way. However they are careful about doing this as it does not just help your lost pilots find their way home but is also used by enemy pilots to find you.
Not exactly your question, but passenger and cargo planes used celestial navigation at sea up until around the 1960s. Some of the earliest 747s had a sextant port built in.
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