by Jonathan M. Stern
Local Control (or Tower)
Local Control has the responsibility for instructing all airborne aircraft within the vicinity of the airport, including instructions for aircraft to takeoff and land. The local controller may have to coordinate with the departure and arrival controllers in sequencing arriving and departing aircraft, and with the ground controller to authorize aircraft to taxi on or across active runways.
When ready for takeoff (the Before Takeoff checklist is successfully completed), takeoff clearance is requested from the tower. In real life, the tower controller assumes that jet-powered aircraft are ready for departure when they arrive at the runway and will frequently clear them for takeoff without such clearance first being requested. With propeller-driven aircraft, ATC usually awaits a request for takeoff clearance. This is done because many propeller-driven aircraft conduct engine runups just prior to takeoff. Additionally, so as not to miscommunicate with departing aircraft, the controllers do not use the word takeoff until they are actually clearing an aircraft to do so. Instead, the word depart or departure is used.
As Lear 12345 approaches runway 28R, the crew requests departure clearance and the Tower Controller advises the flight to place the airplane in a position from which it is ready for takeoff upon further instruction:
"Pittsburgh Tower, Lear 12345 is ready for takeoff."
"Lear 12345, Pittsburgh Tower, taxi into position and hold."
Lear 12345 may be delayed momentarily for numerous reasons. The departure controller may have requested a specified amount of separation between departing aircraft. Another aircraft could be flying in the vicinity of the departure end of runway 28R. An instruction to taxi into position and hold authorizes the aircraft to taxi onto the runway but does not authorize a takeoff. At the appropriate time, the tower controller clears Lear 12345 to take off.
"Lear 12345, after departure fly heading 2-8-0, cleared for takeoff."
"Lear 12345, heading 2-8-0, roger, cleared for takeoff."
As Lear 12345 begins the takeoff roll, the cab coordinator, a controller in the tower cab who coordinates between the tower and the radar room, calls the radar room on an inter/intra facility phone line ("interphone") to advise that Lear 12345 is taking off. This way, the departure controller anticipates fitting the aircraft into the flow of departure traffic.
After takeoff, the flight crew continues on a heading of 280 degrees, and initiates a climb to 5,000 feet (refer to the clearance that the Clearance Delivery Controller issued). When the flight passes the airport boundary, the tower controller instructs the crew to contact departure control.
"Lear 12345, contact Departure Control on frequency 124.75."
"Lear 12345, roger."
Example: "Cessna N2001Z, Washington Tower. Taxi into position and hold runway three six. Traffic, a DC-9 landing runway 33. Be ready for immediate takeoff. (Pause). Cessna N2001Z, caution wake turbulence DC-9 landed runway three three, cleared for immediate takeoff. Traffic is a United seven twenty seven two mile final runway three six." (See Fiqure 11.2.)
Figure 11.2. The tower controller may delay your departure for traffic, in this case a DC-9-30, landing on another runway.