https://phys.org/news/2019-01-amelia-earhart-hard.html

From the early years of aviation up until about 2000, the main way pilots navigated was by playing connect-the-dots across a map. They would use radio direction-finding equipment to follow a route from an airport to a radio-transmitting beacon at a fixed location, and then from beacon to beacon until reaching the destination airport. Various technologies made that process easier, but the concept was still the same. That system is still in use, but decreasingly so as new technologies replace it.

In the first few years of the 21st century, pilots for major airlines began to use the United States' Global Positioning System and other similar systems that use signals from orbiting satellites to calculate the plane's position. GPS is more accurate, letting pilots land easily in bad weather conditions, without the need for expensive ground-based radio transmitters. Satellite navigation also lets pilots fly more directly between destinations, because they need not follow the routes from one radio beacon to the next.