A directional beam was an energy transmission utilized on board starships to obtain a weapons lock on an enemy vessel or other target. On Starfleet vessels of the 23rd century, the ship's navigator was required to manually lock weapons into the directional beam in order to obtain a positive lock.

In 2266, when the crew of the USS Enterprise was forced to destroy a mysterious space buoy which was emitting harmful radiation, Captain Kirk accused the ship's navigator, Dave Bailey, of being slow in his response of locking ship's phasers into the directional beam, and subsequently ordered a series of simulated attacks in order to increase the crew's proficiency rating. (TOS: "The Corbomite Maneuver")