How do planes land and navigate?

(1) How does the plane land safely on a runway with a width of only a few dozen meters after arriving at the airport, especially in weather conditions with low visibility such as rain and snow? This is inseparable from the "instrument landing system". The instrument landing system mainly consists of the glideslope and the localizer. The two "brothers" "stand" at both ends of the runway. The localizer controls the landing direction of the aircraft to accurately align the aircraft with the center line of the runway. The glideslope controls the aircraft's glide angle, allowing the aircraft to glide along the specified glide slope until Landing. With the help of these two and other auxiliary equipment, even if the runway cannot be clearly seen, the pilot can adjust the direction and angle of the aircraft according to the instructions of the instrument, so that the aircraft can accurately align with the runway, and finally land safely.

(2) The earliest old-fashioned aircraft relied on the pilot's visual navigation. When flying in the sky, the pilot held a map in his hand and looked for landmarks. There is also compass navigation: on bombers and passenger planes, specialized navigators can use speed-direction to calculate the aircraft's orientation. Of course, this method requires that the aircraft can only fly in a straight line. The navigator must constantly read the aircraft's speed, direction and other data and display it on the navigation chart. It is more accurate to mark it continuously and add visual correction of landmarks.

Radio navigation was developed during World War II, that is, multiple radio signal stations were set up on the ground, and the aircraft had a radio compass, which could directly read the position of the radio transmitting station. As long as the specific position of the two radio stations and the direction read by the radio compass were known, The position of the aircraft can be found by triangulation on the picture. Before GPS, it had always been the primary method of in-flight navigation.

In civil aviation or during the Cold War, the Chinese and Russian air forces used ground navigation, that is, ground radar tracks aircraft. The radar can accurately measure the direction and distance of the aircraft. The location of the aircraft can be directly known on the map, and the pilot can be informed through ground command.

The best navigation now is GPS. In fact, the principle is the same as radio navigation, but it is more automated. But radio navigation and ground radar navigation are still indispensable.