Suppose you are flying across the United States, perhaps from New York to San Francisco. Your flight, like every other commercial airline flight, follows a typical profile:
- Preflight -This portion of the flight starts on the ground and includes flight checks, push-back from the gate and taxi to the runway.
- Takeoff - The pilot powers up the aircraft and speeds down the runway.
- Departure - The plane lifts off the ground and climbs to a cruising altitude.
- En route - The aircraft travels through one or more center airspaces and nears the destination airport.
- Descent - The pilot descends and maneuvers the aircraft to the destination airport.
- Approach - The pilot aligns the aircraft with the designated landing runway.
- Landing - The aircraft lands on the designated runway, taxis to the destination gate and parks at the terminal.
While you prepare for your flight by checking your bags and walking to the gate, your pilot inspects your plane and files a flight plan with the tower -- all IFR pilots must file a flight plan at least 30 minutes prior to pushing back from the gate. Your pilot reviews the weather along the intended route, maps the route and files the plan. The flight plan includes:
- Airline name and flight number
- Type of aircraft and equipment
- Intended airspeed and cruising altitude
- Route of flight (departure airport, centers that will be crossed and destination airport)
Your pilot transmits this data to the tower.
In the tower, a controller called a flight data person reviews the weather and flight-plan information and enters the flight plan into the FAA host computer. The computer generates a flight progress strip that will be passed from controller to controller throughout your flight. The flight progress strip contains all of the necessary data for tracking your plane during its flight and is constantly updated.
Once the flight plan has been approved, the flight data person gives clearance to your pilot (clearance delivery) and passes the strip to the ground controller in the tower.
The ground controller is responsible for all ground traffic, which includes aircraft taxiing from the gates to takeoff runways and from landing runways to the gates. When the ground controller determines that it is safe, he or she directs your pilot to push the plane back from the gate (airline personnel operate the tugs that actually push the aircraft back and direct the plane out of the gate area). As your plane taxis to the runway, the ground controller watches all of the airport's taxiways and uses ground radar to track all of the aircraft (especially useful in bad weather), ensuring that your plane does not cross an active runway or interfere with ground vehicles. The ground controller talks with your pilot by radio and gives him instructions, such as which way to taxi and which runway to go to for takeoff. Once your plane reaches the designated takeoff runway, the ground controller passes the strip to the local controller.
The local controller in the tower watches the skies above the airfield and uses surface radar to track aircraft. He or she is responsible for maintaining safe distances between planes as they take off. The local controller gives your pilot final clearance for takeoff when it is deemed safe, and provides the new radio frequency for the departure controller. Once clearance is given, your pilot must decide if it is safe to take off. If it is safe, he accelerates the plane down the runway. As you leave the ground, the local controller hands your plane off electronically to the departure controller at the TRACON facility that services your departure airport, but still monitors the plane until it is 5 miles from the airport. Your pilot now talks with the departure controller.