Before the 1930s, pilots relied solely on sight to fly a plane and had little training in reading instruments to navigate through the air. As a result, a nasty turn in the weather could end in a plane crash and the loss of valuable lives and equipment. A breakthrough occurred in 1929 when Edwin Albert Link developed a small flight simulator known as the Link Trainer. The Link Trainer resembled a little blue, almost cartoon-like, plane, earning it the nickname the "blue box." It provided a safe environment for pilots to learn how to fly solely through reliance on the instrumentation found in their planes.
The flight simulator's most crucial role was to train pilots fighting during World War II. It was used in virtually every country involved in the war, including the United States, Germany, Australia, and Japan. Each country made its own versions and models. In the U.S., the Army Air Corps — the flying branch of the military that originated before the United States Air Force — used several models known as the ANT-18s. The wooden plane itself simulated flight and working instruments. Outside the plane, an instructor acted as ground control and communicated with the pilot through a pair of headphones and a microphone.
To create the Link Trainer, Ed Link used skills he'd picked up working on musical organs. The large bellows and pumps that moved air throughout the organ served as inspiration for the design of the Link Trainer and the system that made it move. The original version moved up and down by a system of bellows that inflated and deflated underneath it. As technology advanced, so did the systems used to simulate flight and movement for pilots sitting inside the trainer.
Instrument flight differed from visual flight in several ways. Flying by sight involved viewing the surrounding cloud cover and other visual markers to make judgments about elevation and how to adjust the plane. If fog rolled in or a storm brewed up out of nowhere, the pilot lost his visibility and ran the risk of crashing. Instrument flying relied not on what the pilot could see, but on what information his plane picked up. The dashboard provided a vast readout of altitude, current coordinates, and other conditions which he could use to determine exactly how to adjust the plane.
When using instrument flight, the pilot could also radio down to control towers for further instructions and use a radar readout to view other planes in his path. Even in the foggiest weather the pilot could still fly the plane without the high risk of crashing. The Link Trainer allowed pilots to learn this skill without risking their lives by flying in a real plane until they had mastered the technique. The technology saved countless lives throughout WWII, and more advanced simulators exist today to train and educate pilots.