From pre-flight to landing,
all Instrument Flight Rule (IFR) flights are conducted with controller-pilot
communications. An IFR flight over a long distance requires many communications
with many different controllers.
the flight plan is filed for a commercial jetliner and the aircraft preflight is
completed, the pilot is ready to taxi. A call is made to Clearance Delivery in
local control (the airport's control tower) for either verification of the
"clearance filed" or to receive a "modified clearance." Pilots are encouraged to
file for "preferred" routes, if there are any. Pilots always like to hear
"cleared as filed" as this means their flight plan was received without
requiring any changes. When pilots receive an amended clearance, they copy and
read back to verify. The controllers will warn a flight crew if the new
clearance is a long or complicated notation. A clearance delivery controller at
Chicago's O'Hare (ORD) airport would warn a pilot of complicated changes with
the statement, "Hope you have a sharp pencil handy." The crew receiving the
clearance would recognize that they would have to listen carefully and write
After the pilot has clearance, he/she is instructed to contact
ground control in local control (the airport's control tower) on the frequency
given by the clearance delivery controller. Next, the ground controller clears
the pilot to taxi to the takeoff runway. At large airports this can take a
considerable amount of time, involving many turns on many taxiways with many
stops (for further clearance if the taxi path crosses runways along the way).
All clearances have a "cleared to" phrase that gives further directions on how
to proceed once the aircraft arrives at that point.
Once the pilot is at
the takeoff runway in the run-up area, he/she contacts the airport tower. When
the tower controller clears the aircraft for takeoff, the controller also
instructs the pilot as to the heading and altitude to climb to after takeoff.
Clearance for many flights specifies a standard Departure Procedure (DP).
After takeoff and the initial
climb out from the departure airport, the local controller hands off the flight
to the departure controller located in the Terminal Radar Approach Control
(TRACON). The "hand-off" consists of the local controller telling the pilot to
contact departure control and giving the radio frequency to which the pilot must
switch. This hand-off also takes place electronically as the aircraft's
transponder code is received by the controller in the TRACON. The signal appears
on the controller's radar screen as a "target" with its data block. The pilot
then contacts the departure controller located in the TRACON who then provides
necessary altitude or heading changes to position the aircraft for its next
flight phase: en route. The departure controller then hands off the flight to a
controller in an Air Route Traffic Control Centre (ARTCC).
Click image for a larger view
The ARTCC controller then monitors the aircraft along the en route portion of
the flight. A coast-to-coast flight will fly through many different ARTCC
sections before the flight is handed off to an approach controller. The original
flight clearance that was given probably contained a Standard Terminal Arrival
Route (STAR) for the arrival phase of the flight. If there are no delays or
weather problems, the STAR will be routinely followed.
Click the image for a full view
The Approach Controller gives the pilot descent altitudes and vectors
(headings) to a final approach fix. When the aircraft arrives at the final
approach fix, it will be cleared to fly a published approach. The flight will
next be handed off to the destination airport's tower controller for landing
The tower controller clears the flight to land. Upon
landing, the tower controller directs the pilot to an exit taxiway. The pilot
also receives the next radio frequency to which he/she must switch the radio in
order to contact the ground controller.
After exiting the runway, the
pilot contacts the ground controller for taxi clearance and gate instructions.
The pilot parks the aircraft at the gate, terminating the flight.