Aerial units are often tasked to assist in vehicle pursuits. Air support allows ground units to disengage and follow from a discreet distance, hopefully making the pursuit less dangerous while still allowing ground units to be able to close in quickly as directed to apprehend suspects. Aerial surveillance also allows the police to anticipate the direction of the pursuit, and position ground units ahead of the suspect to block roads or deploy spike strips. Aerial units can also be used to efficiently locate missing persons.