Air Traffic Control

Air Traffic Controllers play a major role in aiding pilots to undergo successful flights. Comprehending the nature and the rationale of ATC enhance the safe operation of any flight and make it easy to understand the meaning of each communication phrase. In addition, it reduces the workload on both pilots and controllers. This workload reduction saves times for pilot, for other required tasks especially during emergency phases, and for ATC to assist other traffic especially distressed aircrafts.

In an airport, the air traffic services are provided through the following air traffic control units:

• Airport control tower
• Approach control Office
• Area control center

Airport control tower and approach control office are responsible for the controlling aircrafts operating in the control zone, while the terminal control area and the area control center are responsible for controlling aircrafts operating in the control area.

ATC units continuously provide separation for IFR flights. This separation has criteria and minima the ATC abide with. The separation minimums are as follows:

• Vertical separation (1,000 or 2,000)
• Horizontal separation and will be based on time or distance

In order to achieve the required separation minima, the aircraft will be instructed to fly a certain heading, at a certain speed, and/or climb or descend to a certain altitude or flight level.

Communications between ATC and pilots are mostly clearances. ATC clearance has a very specific phraseology as it carries important information in a very short time to be heard and understood by pilots. Most of ATC clearances are similar in structure as well as the read back of the clearance should be in the same structure as the issued clearances. Any ATC clearance usually contains the following in the same sequence:

• Station Name
• Aircraft Identification
• Clearance Limit
• Route of Flight
• Assigned initial or final Cruising level or altitude

These clearance contents apply for an ATC clearance. Pilots are always encouraged to read back the ATC clearances as it is. Not abiding with the standard terminology requires clarification from both sides and consumes time and effort from both parties.

There are two types of flight rules for aircraft to follow, either visual Flight rules (VFR) or Instrument Flight Rules (IFR). Although most of the jet aircraft fly under IFR, it is advisable to fly visual approaches

VFR flights are allowed to take off or land at an aerodrome within a control zone, or enter the traffic zone, if:

• The cloud ceiling is more than 1500ft
• The ground visibility is more than 5 km
• Flying below FL 200
• Cruising with speeds less than transonic and supersonic speeds

Other than the above criteria for VFR, IFR is applied. Usually, IFR flights are under radar coverage. Other than being authorized otherwise, pilots under IFR shall not be flying at a level below the minimum flight altitude established by the state, whose territory is overflown

In case of emergency, the quick coordinated action between ATC and pilots reduce the workload for both. There are some initial actions expected of them. The actions are coupled with duties to avoid mid-air collisions.

When the aircraft loses two-way radio communication capabilities while operating in VFR conditions, the airport tower uses different light signals to relay instructions to the aircraft as follows