Air traffic control relates to the commercial and military exploitation of airspace by aircraft. Whereas on the ground, drivers control their vehicles themselves and more or less respect a common set of laws in order to prevent accidents, pilots can not rely on their eyes or on-board instrumentation alone to avoid collisions with other planes, helicopters or obstacles such as skyscrapes, mountains etc. It takes assistance from ground-based air traffic controllers who see the “big picture”, supported by technical instrumentation such as radar, radio beacons etc. In addition, ATC systems are used that serve different purposes, eg. security functions (predicting aircraft positions and possible collisions), airspace management functions (when does which flight occupy which flight route), weather forecasts (how are the weather conditions at the plane’s destination airport).
Naturally, such ATC systems can be of critical importance, similar but not quite as criticial as the technology in nuclear power plants, spacecraft etc. On the other hand, ATC systems like any other computer system can be based on existing technology only. On second thought, it may seem understandable that an ATC application can not run on your superstore’s $199 PC running a Windows operating system.
But did you know that almost all ATC systems in Germany rely on Linux? Not because of reduced costs – for one thing, the recognized higher software quality resulting from the Open Source development process plays an important part. But most of all, having access to the source code is critical when it comes to reaching a degree of reliability that is crucial for ATC operations.
If this all got you interested: this 2010 Linux Collaboration Summit presentation has more details.