What does TACAN Air-to-Air mode measure?

TACAN, or Tactical Air Navigation, is primarily designed to provide accurate distance and bearing information. In Air-to-Air mode, TACAN enables aircraft to measure the range to another aircraft, which is crucial for various operational scenarios, such as formation flying and air combat. This system functions by using onboard equipment to triangulate the position of another aircraft against a known reference point, allowing pilots to obtain reliable data about their distance from that aircraft.

The focus on range measurement is important for maintaining safe separation, coordinating maneuvers, and enhancing situational awareness in dynamic environments. Unlike the other options, which pertain to parameters that are either not measured by TACAN or extend beyond its intended operational scope, accurately determining range is a fundamental aspect of its functionality in Air-to-Air applications.