An impact alert was an alert to notify crewmembers of a starship when it is about to collide with another spatial object, like another vessel. In 2233, the viewscreen of the USS Kelvin notified Captain George Kirk of an impact alert with the Narada after Kirk had set the Kelvin on a collision course with the enemy vessel. Twenty-five years later, an impact alert was declared on the bridge of the USS Enterprise when it warped right into a debris field of its fleet. While en route to Titan, an impact alert was declared right before the ship dropped out of warp. (Star Trek)