Three generations of approach charts used for instrument flying --- 1939, 1980, and 2014 --- at El Paso, TX.
The first chart was tucked into the back of an old flying book I picked up on eBay, and I thought it would be interesting to compare it with more modern examples. This approach used the low frequency radio range system of the 1930s and 1940s. The system transmitted directional radio signals along four courses. Pilots navigated by audio, listening to morse code to determine their position. If you were off course, you would hear the morse signal for the letter A (dot dash) or the letter N (dash dot), depending on which of the four quadrants you were in. To make it interesting, you could be NW or SE of the station and it would sound the same, the letter A being broadcast in both quadrants. Same thing for the other two quadrants, except with the letter N. If you were on course (any of the four), you would hear a steady hum. Distance was determined by timing based on speed. In the clouds, with mountains nearby, it wasn't for the faint of heart!
The second is for a precision ILS approach using ground-based navaids, a system which began to see widespread use around the 1950s and still very much in use today. Using this system, you can safely land in extremely low visibility.
Last is a more current example of finding your way down through the clouds: a satellite-based GPS approach, depicted on an electronic "chart" using an iPad. Gee whiz.