AIR TRAFFIC ONTROL

Air Traffic Control Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is: to separate aircraft to prevent collisions to organize and expedite the flow of traffic to provide information and other support for pilots when able. Air traffic controllers are the people who operate the air traffic control systems to expedite and maintain a safe and orderly flow of air traffic and help prevent mid-air collisions.

Air Traffic Control System

Transmission of Signals

Air Routes in Arrival & Departures

Air Traffic Control Tower

Flight Profile

Various Flight Profiles 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.

Objectives of the air traffic services The objectives of the air traffic services shall be to: prevent collisions between aircraft. prevent collisions between aircraft on the maneuvering area and obstructions on that area. c) expedite and maintain an orderly flow of air traffic. d) provide advice and information useful for the safe and efficient conduct of flights. e) notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required.

Divisions of the air traffic services The air traffic services comprise of three services identified as follows: Air traffic control service Area control service Approach control service Aerodrome control service Flight information service Alerting service

Air traffic control service Area Control Service: The provision of air traffic control service for controlled flights, except for those parts of such flights which are under the jurisdiction of Approach Control or Aerodrome Control to accomplish following objectives: a) prevent collisions between aircraft b) expedite and maintain an orderly flow of air traffic Approach control service: The provision of air traffic control service for those parts of controlled flights associated with arrival or departure. Aerodrome control service: The provision of air traffic control service for aerodrome traffic, except for those parts of flights which are under the jurisdiction Approach Control.

Flight information service: Provide advice and information useful for the safe and efficient conduct of flights. Alerting service: Notify appropriate organizations regarding aircraft in need of search and rescue aid and assist such organizations as required.

Visual flight rules(VFR Flights) Visual flight rules (VFR) are a set of regulations which allow a pilot to operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than Basic VFR Weather Minimums, as specified in the rules of the relevant aviation authority. If the weather is worse than VFR minimums, pilots are required to use Instrument Flight Rules. Meteorological conditions that meet the minimum requirements for VFR flight are termed visual meteorological conditions (VMC). If they are not met, the conditions are considered instrument meteorological conditions(IMC), and a flight may only operate under IFR. VFR rules require a pilot to be able to see outside the cockpit, to control the aircraft's attitude, navigate, and avoid obstacles and other aircraft. A VFR flight is "conducted in accordance with the visual flight rules

An aircraft operated in accordance with the visual flight rules which wishes to change to compliance with the instrument flight rules shall- Communicate the necessary changes to be effected to its current flight plan or Submit a flight plan to the appropriate air traffic services unit and obtain a clearance prior to proceeding IFR when in controlled airspace.

VFR Rules Except when a clearance is obtained from an air traffic control unit, VFR flights shall not take-off or land at an aerodrome within a control zone or enter the aerodrome traffic zone or traffic pattern: When the ceiling is less than 450M(1550 Ft) or When the ground visibility is less than 5KM. VFR flights shall not be operated between sunset and sunrise, except when exempted by air traffic control for local flights and such training flights of flying club aircraft as may be cleared by air traffic control. VFR flights can not be operated- Above FL50 At transonic and supersonic speeds More than 100 NM seaward from the shoreline within controlled airspace. Expect when necessary for take-off or landing or except by permission from appropriate authority, a VFR flight shall not be flown- Over congested area of city, town or settlements or over an open-air assembly of persons at a height less than 300M above the highest obstacle within a radius of 600M from the aircraft.

INSTRUMENT FLIGHT RULES (IFR FLIGHTS) Instrument flight rules (IFR) are regulations and procedures for flying aircraft by referring only to the aircraft instrument panel for navigation. Even if nothing can be seen outside the cockpit windows, an IFR-rated pilot can fly while looking only at the instrument panel. An IFR-rated pilot can also be authorized to fly through clouds, using Air Traffic Control procedures designed to maintain separation from other aircraft. Training is normally done in simulated IFR conditions with training aids such as block alls to help a pilot concentrate only on the instrument panel. Most scheduled airline flights operate under IFR. Visual Flight Rules (VFR) are often used for sight-seeing flights, aerial photography, or lift services for parachute jumping. Pilots flying under VFR are not permitted to fly through clouds. Many non-commercial, private recreational aircraft also operate under VFR whenever the sky is clear. Under VFR, the pilot is primarily responsible for navigation, obstacle clearance and maintaining separation from other aircraft using the see-and-avoid concept.

IFR Rules All aircraft shall be equipped with suitable instruments and navigation equipment appropriate to the route to be flown. Except when necessary for take-off or landing or when specifically authorized by the appropriate authority, an IFR slight shall be flown at a level that is not below the established minimum flight altitude or where no such minimum flight altitude had been established- Over high terrain or in mountainous areas, at a level which is at least 600M above the highest obstacle located within 8KM of the estimated position of the aircraft. Elsewhere at a level at least 300M above. An aircraft electing to change the conduct of flight from IFR to VFR shall notify the app. Air traffic services unit specifically that the IFR flight is cancelled and communicate the changes to be made to its current flight plan. When an a/c operating under IFR is flown in or encounters visual meteorological conditions, it shall not cancel its IFR flight rules unless it is anticipated and intended that the flight will be continued for a reasonable period of time in interrupted visual meteorological conditions

Instrument Flight panel and Enroute Guidance

Types of Airspace Based on ATC usage: Controlled Airspace: ATC services are provided throughout the majority of airspace, and its services are available to all users (private, military, and commercial). When controllers are responsible for separating some or all aircraft, such airspace is called "controlled airspace“. Uncontrolled Airspace: In contrast to "uncontrolled airspace“ is the airspace, where aircraft may fly without the use of the air traffic control system.

Based on ATC Services(India): Class D: IFR and VFR flights are permitted and all flights are provided with air traffic Control service, IFR flights are separated from other IFR flights and receive traffic information in respect of VFR flights. VFR flights receive traffic information in respect of all other flights. Airspaces in terminal areas, control areas, control zones and aerodrome traffic zones have been classified and designated as class D airspace. Class E: IFR and VFR flights are permitted, IFR flights are provided with air traffic control service and are separated from other IFR flights. IFR flights receive traffic information in respect of VFR flights, VFR flights receive traffic information in respect of all other flights, as far as is practical. Class E is not be used for control zones. Airspaces in designated ATS routes outside terminal areas, control areas and control zones, where air traffic control service is provided, have been classified and designated as class E airspace.

Class F: IFR and VFR flights are permitted. All IFR flights receive an air traffic advisory service and all flights receive flight information service, if requested. Airspaces in designated ATS route segments outside terminal areas, control areas and control zones, where air traffic advisory service is provided, have been classified and designated as class F airspace. Class G: IFR and VFR flights are permitted and receive flight information service if requested. Airspaces other than those in Class D, E and F have been classified and designated as class G airspace.

Application of air traffic control service Air traffic control service shall be provided: a) to all IFR flights in airspace Classes D and E b) to all VFR flights in airspace Classes D c) to all special VFR flights d) to all aerodrome traffic at controlled aerodromes.