What is a computer navigation fix used for in aircraft navigation?

• A. A method of calibrating autopilot for heading control.
• B. A ground-based beacon used for distance measurement during approach.
• C. A point used to define a navigation track for an airborne computer system such as GPS or FMS.
• D. An approach procedure for emergency diversions.

Answer: (C)

A navigation fix is a defined reference point along a route that the aircraft’s navigation computer uses to map and follow the flight path. The onboard systems, like GPS or an FMS, load a sequence of fixes into the flight plan; by knowing the coordinates of each fix, the system can determine the airplane’s position, compute the course between fixes, and calculate distances and ETA. This makes automated navigation precise and predictable, allowing the aircraft to stay on the planned track. The other options don’t fit because they describe equipment or procedures not used as reference points for defining a navigation track—calibrating autopilot heading, ground-based distance measurements like DME, or an emergency diversion procedure aren’t about defining a route via a fix.