CHAPTER 5 Interrupts Every pilot is taught to keep his eyes constantly scanning the horizon, looking for visual clues about position and direction of flight, and looking for other airplanes. But he also needs to check the airplane instruments momentarily to verify his speed and his altitude and keep an eye on the map. Now and then there might be the need to focus longer on one of the inputs and it is essential to learn how some instruments need a more frequent check then others, depending on the phase of the flight and a number of other conditions. In other words, pilots need to learn to multi-task, assigning the correct priority to each instrument and optimizing the use of time so as to always stay ahead of the machine. In the world of embedded control, for reasons of efficiency, size and ultimately cost, the smallest applications, which happen to be implemented in the highest volumes, most often cannot afford the "luxury" of a multi-tasking operating system and use the interrupt mechanisms instead to "divide their attention" between the many tasks at hand. Flight Plan