ABSTRACT
Alarms or alerts of various types are included in many systems in order to call operators’ attention to important information. In aircraft cockpits, Ground Proximity Warning Systems (GPWS) are present to warn pilots when they are too close to the ground or when their vertical pro”les show them descending toward the ground too quickly. Nuclear power plant operators are surrounded by alerts that tell them of unwanted states on various parameters for numerous different pieces of equipment. Air traf”c control stations are equipped with alerts that ¢ash aircraft symbols when the computer detects they are on a collision course (Figure 9.1).
