Bearings were used when defining the direction at which another object in space was located in relation to the ship or when the ship made a course correction in its current heading. (TOS: "Balance of Terror") Bearings have also been used by away teams on the surface of a planet to indicate a direction. (TOS: "By Any Other Name")
Bearings are given in a combination of two 360-degree angles:
- "111-mark-14." (TOS: "Balance of Terror")
- "341-mark-20. Range 12 kilometers." (DS9: "The Search, Part I")
- "320 degrees-mark-2." (Star Trek)
- "240 degrees-mark-6, port." (Star Trek VI: The Undiscovered Country)
- "123 degrees-mark-18. Range 90 thousand kilometres." (TOS: "The Changeling")
The first use of the term bearing to indicate a direction occurred in Star Trek: The Original Series episode "Balance of Terror". The meaning of bearings has been further defined in the writer's guides and several reference books, such as Star Trek: The Next Generation Technical Manual (pg. 36).
Bearing 000-mark-0 is directly in front of the ship and bearing 180-mark-0 directly behind the ship. Coming about to bearing 090-mark-0 would be a sharp turn to the right or starboard. Coming about to bearing 270-mark-0 would be a sharp turn to the left or port. The second figure after the "mark" is the elevation angle. Coming about to bearing 000-mark-90 would be tilting the ship directly upwards and 000-mark-270 directly downwards.