An Inexpensive Terrain Awareness and Warning System for Small Aircraft

For pilots the importance of knowing their height (distance above the ground) cannot be minimized. An error in determining height can easily prove fatal. Commercial and military aircraft usually have radio altimeters to determine their height. These units cost in the thousands of dollars, are a structural part of the aircraft, and require FAA approval. However, radio altimeters are generally not available to private pilots or small aircraft because of their excessive cost. Important advances have occurred in the last two decades that have made it possible to construct portable devices that can calculate an aircraft’s height. These advancements are the Global Positioning System (GPS), powerful microcontrollers, programmable flash memory, and color LCD displays. Using this technology along with publicly available digital elevation data it is possible to build an inexpensive, accurate embedded device that can calculate height and other flight parameters. Such a device is not dependent upon FAA approval and can be used in any aircraft.