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The Airline Pilots Day and Air Traffic Control This is an easy guide to how the Pilot/Air Traffic Control System works. The pilots arrive about 1 hour before the flight. The pilots then go to the Operations Room and gather and study the weather and routings for the flight. The pilots then check the fuel plan allowing for delays and diversions noting any unserviceable navigation aids on route etc. If an aircraft is flying in Controlled Airspace a flight plan must be filed in advance. This is so Air Traffic Control can plan their movements from Ground Control, through the Tower Control, to all the Air Traffic Control Centres on route. Finally the Approach Control,Tower and Ground Control at the destination airport . Because we are flying today on a regular flight, the flight plan is stored in the Air Traffic Control computer and pending strips are automatically printed as a warning to all Air Traffic Centres handling the flight sometime before the departure time to help controllers plan. The pilots tell the dispatcher how much fuel is required. The pilots then go to the aircraft to prepare it for flight. About fifteen minutes before departure time, if everything is running to time, the pilots will call Clearance Delivery by radio and request their clearance to their destination . ATC will give the clearance and the transponder code for the flight at this stage to the pilots. This includes which Standard Instrument Departure (SID) procedure they will be using on take off. Sometimes the pilot is given a take off time known as a slot time. This is where an aircraft has to take off at that time or lose the clearance and go to the back of the line again .This is normally done at busy flow times . The dispatcher arrives just before departure time, the load sheet is checked to see the aircraft weight and balance is correct for every stage of the flight . If all is well, the doors are closed and the ground controller is then called. Clearance to push back from the stand is then asked for. Once the tug is removed the pilots call for taxi to the runway. At this point the Air Traffic Control Centre is aware of the pending take off. The computer updates the warning strips for the controllers. As the aircraft taxies out the pilot contacts the Departure Controller in the Tower, this controller will ask for permission from the Air Traffic Centre to release the aircraft for take off. The pilot will then fly the Standard Instrument Departure SID procedure on take off towards the airways for his flight. The airways are 10 miles wide normally. Low Level Airways normally go up to 24500ft. Upper Airways are above that . Please note Lower airways and Upper Airways do not always follow the same route. In America the Lower ones are Victor Airways, the Higher ones are Jet Ways. Each Airway has a number. It is like a high speed motorway in the sky. Some airways flow in both directions some are one way. Aircraft can fly 1000ft above or below each other. The Tower Controller will ask the Centre Controller to accept the aircraft just before take off. As soon as the aircraft has left the runway, the pilot will be instructed by the tower to change frequency to the Centre Controller. The Centre controllers will vector the aircraft around other traffic and climb it up to its cruising height.This is done normally in stages with headings and heights to fly given by radio. Eventually the pilots will be told to resume their own navigation according to the flight plan. Each time the aircraft gets to the end of the sector, the controller will hand it off to the next controller. Eventually the aircraft is handed off to Approach Control of the destination airfield. Approach Controllers give the pilot headings to fly, once the aircraft is on final approach they are instructed to contact the tower. The tower at the arriving airport clears the pilot to land. Once landed and clear of the runway, the ground controller takes over until the aircraft has parked. Then the process starts all over again. At major airports pilots fly Standard Arrival Routes from the Airway to a holding fix. This is like a filter. These routes are known as STARS or Standard Arrival Routes. Please Note, if it is a clear day and the the traffic is light the controller may give the aircraft a straight in approach giving headings to fly to get the aircraft onto the approach centre line. At some airfields in bad weather the pilots have to land using an instrument approach procedure. The details on this are carried in charts on the aircraft. Occasionally the airliner will fly a circuit procedure just like a light aircraft does. The pilots may change radio frequencies say 30 times in a flight to the Middle East from the UK. The controllers job is to keep the aircraft separated by 3 miles at the same height or 1000ft above or below any aircraft or other local practice that is authorised. On departure the pilot must stick to the Standard Instrument Departure (SID) unless cleared by a controller or a serious incident could occur. Example take the Midhurst Departure (SID) from Heathrow. Heathrow outbound traffic crosses Midhurst level at 6000ft normally going South . Gatwick outbound traffic crosses Midhurst at 5000ft going West and Gatwick inbound traffic crosses near Midhurst going South East at Flight Level 70 (7000ft). Arriving traffic must stick to the Standard Arrival Route (STAR). It could ruin a good day if you get it wrong. Whilst Instrument Approach Charts are made for most airports ,Gatwick and Heathrow is so busy that they are rarely used. The aircraft are radar steered by controllers into line for landing,otherwise delays would be massive and the back of the jam would mean holding stacks full everywhere . Pilots do check the charts for safety height and navigation information on the approach as the go around procedure is also contained on them . Once round the holding stack takes 4 minutes on a race track pattern if an aircraft has to hold. A Lesson on holding is going to be included shortly. Crossing the Atlantic is a subject of its own and is contained in a link from the Flight School . Because Air Traffic is so dense in Europe, pilots have to fly standard routes and not direct tracks between airports This is covered in more detail in other items. On route the pilots monitor the weather for different airports using VOLMET which is a VHF radio frequency that gives weather reports for groups of airports in an area . In the Atlantic HF radio is used with different airports groups broadcast at different times of the hour. ACARS data link will also be used now. Nearer the airport pilots can get ATIS broadcasts.
Note that some airports agents act on behalf of an airline. They are responsible for filing the flight plan and giving the pilots the information required for the flight. Sometimes this information may be delivered to a hotel if pilots are night stopping. Other times this is faxed from the Airlines Operations room to the pilots via the agent. Further reading on Air Traffic Control
may be found on
the following links :- http://www.caa.co.uk/ http://www.bwatch.freeserve.co.uk/ http://agrino.org/cyatca/ There is an Air Traffic Control Web Ring. This can be accessed from most of these sites. There are some excellent articles here, written by Controllers from around the world ,describing their own area. If you read the Radio Procedure lesson this subject will help you understand it.
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