This tutorial about the use of computers in airplanes is intended primarily for people with a computer science background who would like to learn more about this computer-dependent application domain. Novices from other disciplines will likely also find it useful in understanding the basic ideas and vocabulary associated with the field. It is suitable for a final-year undergraduate course or a first-year graduate course in avionics systems, or as an introduction for an engineer entering the avionics field.

The term avionics is a contraction of aviation electronics; digital avionics is that part of the avionics field concerned with digital, usually computerized, technology. This is an important field because modern aircraft use digital avionics extensively for a wide variety of applications. Modern autopilots, for example, are sophisticated devices capable of reducing pilot workload dramatically. With a few rare exceptions, autopilots are completely computerized.

In practice, most cockpit functions are computerized. In recent years, computer age technology has largely replaced older, electro-mechanical approaches. Where once aircraft cockpit displays were mostly mechanical dials and graphics, these systems have quickly given way to glass cockpits—ones in which displays are presented on monitors similar to those found on personal computers.

The impact of computer technology extends beyond cockpit displays; the term also applies to the use of computers in the aircraft structure. In older aircraft, pilots controlled the engines and control surfaces—the flaps and the rudder, for example—through mechanical and hydraulic links. The construction costs, maintenance costs, and operational weight of all the different mechanical elements made them targets for replacement with digital technology, which led to the introduction of fly-by-wire control. The term fly-by-wire usually refers to the combination of the communication of control signals over a digital data bus and the use of those signals by computers within the aircraft structure to adjust the control surfaces and engine settings.

As airplanes have thus become flying computer systems, avionics has assumed an increasingly significant role in their development and production. Construction of avionics systems requires large teams of engineers from a wide variety of disciplines, including computer engineering and software engineering. It is impossible for all those engineers to be familiar with the system’s complex goals and operating principles. Still, it would be helpful if they all understood generally what avionics systems are for and how they work. It is with that in mind that the editors and authors produced this ReadyNote.

• John C. Knight is a professor of computer science at the University of Virginia. His research interests are in software dependability; he leads research projects looking to develop industrial-strength formal techniques and techniques designed to enhance the survivability of critical networked infrastructure applications. He holds a BSc in mathematics from the Imperial College of Science and Technology and a PhD in computer science from the University of Newcastle upon Tyne. Before joining the University of Virginia in 1981, he was with NASA’s Langley Research Center. He serves as Editor in Chief of the IEEE Trans. Software Engineering and is a member of the editorial board of the Empirical Software Engineering Journal. Contact him at knight@cs.virginia.edu or http://www.cs.virginia.edu/~jck.
• Elisabeth A. Strunk is a research scientist in computer science at the University of Virginia. She works in the Dependability Research Group, studying the use of formal methods in the construction of safety-critical software systems. Her major projects are architecting embedded software systems to be survivable, verifying that an implementation has properties set out in a system’s formal specification, clarifying the role of natural language in software development, and exploring new technologies for safety cases and failure analysis. She has a BS in mathematics and computer science from Vanderbilt University and an MS and PhD in computer science from the University of Virginia. Contact her at strunk@cs.virginia.edu or http://www.cs.virginia.edu/~eas9d.