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From
your friends at ATCMonitor.com. © 2006 - Reproduction without
permission is prohibited.
LETS TAKE A FLIGHT
Almost every minute, hundreds of commercial aircraft push back from their departure gates and begin flights that follow a common flight profile. This profile is made up of the following phases: preflight, take-off, departure, en route, descent, approach and landing.
As mentioned before, various air traffic controllers handle different stages of the aircraft's trip from take-off to landing. This means that there is never just one controller who handles everything. At any given time, an aircraft crew may talk with several controllers,
many times more than a dozen, throughout one flight. Let's take a closer look.
Here we will discuss an example flight profile of an aircraft traveling from Atlanta, GA (ATL) to Los Angeles, CA (LAX).
1. Preflight phase -This portion of the flight starts on the ground and includes flight checks, push-back from the gate and taxi to the runway.
2. Take-off phase - The pilot powers up the aircraft and speeds down the runway.
3. Departure phase - The plane lifts off the ground and climbs to a cruising altitude.
4. En route phase - The aircraft travels through one or more center airspaces and nears the destination airport.
5. Descent phase- The pilot descends and maneuvers the aircraft to the destination airport.
6. Approach phase- The pilot aligns the aircraft with the designated landing runway.
7. Landing phase- The aircraft lands on the designated runway, taxis to the destination gate and parks at the terminal.
PREFLIGHT PLANNING
The preflight begins with the pilots making a visual inspection of the aircraft.
They check to make sure the aircraft has plenty of fuel, the correct tire pressure, and anything that looks
JDLR (just doesn't look right) . They also check the weight and balance of the aircraft to make sure that the luggage, fuel, and passengers' weight are equally distributed.
Once this is completed, the pilots board the aircraft and enter the cockpit.
After preparing the aircraft and programming the FMS (Flight Management
System computer), they contact ground control, which is usually located in
the control tower, for a departure clearance. The departure clearance is obtained when the pilots communicate with the control tower with
departure clearance information, which consists of:
1) Their aircraft type (e.g. Boeing 737)
2) En route cruising altitude (e.g. 38,000 feet)
3) Departure gate intersection name or course heading (e.g. magnetic compass heading)
4) Destination (e.g. LAX)
5) Confirmation of filed flight plan including flight route.
| Flight plans
are plans filed by pilots with the local regulatory authority (the FAA in
the USA) prior to flying. They generally include basic information such as
departure and arrival points, flight route, cruising altitude, estimated
time of flight, alternate airports in case of bad weather, etc.
Flight plans are typically pre-filed by the air carriers' dispatch
officer, because commercial air traffic follows the same routes
frequently. |
Each flight plan has certain information contained that gives the controllers an idea of the type of equipment that is onboard the aircraft, along with how many passengers are on board, and the route the pilots intend to fly in order to arrive at the final destination. Figure 2 will give you some idea of what a typical flight plan might look like, and then we will discuss what some of the items mean.
Figure 2: Flight plan from Atlanta, GA to Los Angeles, CA
Most of the items on the flight plan are fairly self explanatory, such as the aircraft identification, aircraft type, airspeed en-route, and cruising altitude and so on. However, the Route of Flight section could be a bit confusing if you aren't familiar with the codes used. So let's briefly discuss what our route of flight consists of. Take a look at figure 3.
Figure 3: Route of flight portion of our flight plan
Flight plans are prefiled by commercial airline
dispatchers or automated computer systems. When the pilot is ready to
depart, he or she relays their callsign and "request or clearance to X
destination". The flight plan is called up by a clearance or
ground controller in the tower using the STARS
system.
A flight progress strip is automatically printed to keep a physical
recording of the aircraft in front of the controller's eyes. These data strips include the information about the aircraft's flight profile, which also includes all of the information given when obtaining departure clearance.
In the unlikely event that the STARS screen goes blank, controllers are
trained to use the flight progress strips as backup.
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Flight Progress Strips are merely pieces of electronic data entered into the Control Tower's computer system. However, these strips of data used to be printed on strips of paper, thus the name "Strips". With advances in technology, they are now transmitted via electronic means, giving them less chance for
error. |
After the flight crew finishes their preflight check of the systems, they obtain weather and flight planning information. Then the aircraft pushes back from the gate, receiving instructions from the ground controller in the airport's control tower. The ground controller acts as the overlooking eyes for the pilots while they taxi toward the departure end of the runway, making sure they steer clear of obstructions and other aircraft.
In overcast or similar conditions where visibility is obscured, ground
controllers rely on
ASDE ground surveillance
radar.
Once the pilots reach the departure end of the runway, they contact the control tower and state, for example; "Atlanta tower, Delta flight 542 is ready for departure". Assuming that the area is clear and no other traffic is inbound for landing, or crossing the departure runway, the tower issues Delta flight 542 the statement "Delta 542, you are cleared for departure (or take-off)".
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