Starship Navigation
Navigating a starship requires an enormous amount of data to help pinpoint the vessel's position.

Federation starships navigate the galaxy by combining a massive database of information with sophisticated onboard sensors that can pinpoint the vessel's position accurately. The USS Enterprise NCC-1701-D was capable of calculating its position relative to the galactic center, or another 'fixed' reference point such as Earth, to within 10 kilometers; even at high warp speeds, the ship could determine its location to within 100 kilometers. In close maneuvering of the kind required when docking, the Enterprise was able to maneuver with distances as accurate as 2.75 centimeters.

Navigational operations on the Enterprise were normally controlled from the conn after the commanding officer had given a destination or heading in one of five ways. The easiest method of giving a heading was to name the destination; as soon as this was inputted into the coon, the ship's computers consulted the navigational database and automatically plotted the ship's trajectory. Destinations range from planets and star systems to orbital facilities. If an area as large as a sector was specified, the Enterprise's computers generated a flight path to the center of that area. It was also common for the conn to be given a moving destination such as another spacecraft. As long as the vessel was within sensor range, the computer could plot an intercept course. This kind of order required the conn officer to input either a velocity or an intercept time, so that the course could be calculated relative to the position of the other craft.

Navigation instructions could also be given by specifying a destination's galactic coordinates; however, this method of navigation was rarely used, as it required personnel to either calculate or look up the relevant coordinate information. Navigational orders were more often given as a relative bearing. This consisted of two figures which related to two perpendicular planes around the Enterprise: the first plane was horizontal, the second vertical. Each plane was divided into 360 degrees, with 0 degrees deemed to be straight ahead.

Thus, if the Enterprise was given a heading of 000 mark 0, it would not change its course. On the horizontal plane, values increased to the starboard; in the vertical plane, they increased in the direction above the ship. A heading of 150 mark 0 therefore meant that the ship would turn 150 degrees to starboard but not tilt up or down, and a heading of 150 mark 20 meant that it would turn 150 degrees to starboard and then angle its nose up by 20 degrees. Navigational orders were also given as a heading. Again, this was given as two figures, but these figures related to two planes around a notional line connecting the Enterprise with the center of the galaxy. A heading of 000 mark 0 was directly toward the galactic center. This system was very similar to that used for navigating on a planet's surface, where headings were taken from the northern pole.

The instructions given might be simple, but calculating a course across interstellar distances is an extremely demanding task. This is because it is impossible to maintain an entirely accurate map of the galaxy: all objects within the galaxy are moving in their own direction, and many methods of observing involve a noticeable time lag. Despite these difficulties, the Federation has charted a significant proportion of the galaxy and uses information gathered from subspace relays, Federation vessels, probes, and sensor platforms to ensure that its map - which is known as the galactic condition database - is as up to date as possible. Starfleet's Stellar Cartography division has plotted the position of stars well beyond the reaches of manned exploration. Facilities such as the Argus Array, located on the edge of Federation space, gather data on the position and activity of systems that are light years away from explored space. This data is constantly updated, and the information transmitted back to Federation outposts. Starfleet also updates its galactic database by regularly sending probes and deep space exploration vessels into 'new' regions of space. These vessels, record detailed information which is then transmitted back to other ships and Starfleet installations by subspace radio.

For example, the Stellar Cartography department on the Enterprise constantly observed changes in the position and movement of stellar phenomena. When it reached a starbase or outpost, detailed logs were downloaded and transmitted to Starfleet, and integrated into the galactic condition database. This was in turn distributed to all Federation vessels. Where accurate real-time information was not available, computers worked to predict conditions with reasonable accuracy.

The information which the Enterprise regularly received from the galactic condition database was combined with data gathered by the ship's own sensors on the position of stellar activity such a nebulae, pulsars, and subspace phenomena. These two sources were then combined to more accurately calculate its location and the relative position of its destination. The Enterprise was equipped with various sensors which ensured that reliable positional data could be gathered even in difficult conditions such as magnetic storms or solar flares. During travel, it was essential for the Enterprise's computers to be able to calculate velocity accurately in order to plot the vessel's position. An extensive network of Federation Timebase Beacons allowed the Enterprise to access the absolute time values used to calculate speed. When the vessel was out of contact with the beacons, onboard timebase processors maintained records, but these were subject to some temporal distortion phenomena, and as soon as possible the Enterprise would synchronize them with a timebase beacon. Time distortion was particularly extreme at high impulse speed, but the ship's guidance and navigation subprocessors could largely compensate for this. When calculating a course, the Enterprise crew plotted a flight path that avoided dangerous objects such as stars or other solid bodies. During travel, the computers constantly updated their flight plans, making the necessary course corrections as new information became available.