Avionics Navigation Systems, 2nd Edition

1 Introduction

1.1 DEFINITIONS

Navigation is the determination of the position and velocity of a moving vehicle. The three components of position and the three components of velocity make up a six-component state vector that fully describes the translational motion of the vehicle. Navigation data are usually sent to other on-board subsystems, for example, to the flight control, flight management, engine control, communication control, crew displays, and (if military) weapon-control computers.

Navigation sensors may be located in the vehicle, in another vehicle, on the ground, or in space. When the state vector is measured and calculated on board, the process is called navigation. When it is calculated outside the vehicle, the process is called surveillance or position location. Surveillance information is employed to prevent collisions among aircraft. The humans and computers that direct civil air traffic and most military traffic are located in Air Route Traffic Control Centers on the ground, whereas some military controllers are based in surveillance aircraft or aircraft carriers. Existing traffic control systems observe the position of aircraft using sensors outside the aircraft (e.g., surveillance radars) or reports of position from the aircraft itself. “Automatic dependent surveillance” is a term for the reporting of position, measured by sensors in an aircraft, to a traffic control center.

Traditionally, ship navigation included the art of pilotage: entering and leaving port, ...