Arrival controllers are responsible for separating and sequencing aircraft for approach and landing. The arrivals sector lies within an area of airspace known as the "Terminal Control Area" or TCA for short. This area usually extends 35 nautical miles (nm's) in radius from the airfield in an inverted wedding cake shape however, this number may be less than or greater than 35 nm's. The first layer extends +/- 12 miles in radius and is based at 1200 feet above airport elevation, the second layer extends to +/- 35 nautical miles and is based at 2200 feet above airport elevation. It is worth noting that the departure sector is also controlled within TCA airspace. These two sectors form a unit that is more commonly referred to as the "Terminal Control Unit" or TCU. To assist controllers and pilots during the approach phase published procedures such as "STARS" and "FMS Approaches" have been developed.

Approaches

During the final approach segment of a flight pilots are given specific radar headings, more commonly called "Vectors". These vectors help to establish flights on a specific leg of the approach, they are as follows;

Downwind Leg: Flying a course parallel to the landing runway in the opposite direction of landing.

Base Leg: Flying a course that is at a right angle to the landing runway.

Final Leg: Flying a course that is in line with the landing runway. Centered on the runway and in the direction of landing.

While flying the approach there are various navigational instruments and beacons used to help guide aircraft to the runway. Airports may provide a variety of electronic aids such as the NDB, VOR, or ILS for approaching aircraft. As a result of the various types of instruments available there are many types of approaches in use. They are as follows.

NDB Approach: The "Non-Directional Beacon" approach requires the use of the Automatic Direction Finder (ADF) in the cockpit for bearing information to the runway. Because of it's lack of glide slope (approach path) information it is considered a non-precision approach.

VOR Approach: The "Very High Frequency Omnidirectional Range"  is used much the same as the NDB, however with a greater degree of accuracy. The VOR is used in conjunction with the DME (Distance Measuring Equipment) providing distance to the runway. Since only distance, bearing, and position information is provided, the VOR approach is also considered a non-precision approach.

ILS Approach: The Instrument Landing System is considered a precision approach. The ILS provides both "glideslope" (up/down) and "localizer" (left/right) information via an electronic beam to an instrument in the cockpit. Along this beam there may be up to three "markers", the Outer Marker, Middle Marker, and Inner Marker. Each of these electronic markers has it's own phonetic identifier and provides the distance to the runway. Pilots are often heard reporting their position as they approach or cross a marker. An example of this may be "Toronto Tower, Air Canada 792 crossing "Tango" for runway 06 left". "T" is the outer marker designation for Runway 06 Left at Pearson Airport.

Localizer Approach: This approach is used on occasion when the glide slope portion of the ILS is out of service.

Surveillance Approach: Requiring only the use of an operating two way radio, radar approaches are controller vectored procedures. Controllers guides pilots on course until the pilot is able to make a landing visually. This procedure is used in emergency situations only.

Precision Approach RADAR (PAR): Precision approach radar is used mainly by the military, however some civilian airports are PAR equipped. This approach is very much like a talk down enabling the controller to give the pilot guidance on their heading and elevation. Guidance is terminated when the runway is in sight or a missed approach is executed.

Missed Approach: Canadian Air Regulations (CARS) specifies that landings are governed by published "Decision Height" (DH) and "Minimum Descent Altitude" (MDA) criteria. A pilot is prohibited from continuing a descent below DH or descending below MDA unless the required visual reference has been established and maintained. If these criteria are not met a pilot must execute a missed approach which requires that the aircraft go around. Full power is applied and the aircraft is then directed around to make another approach. Some airlines will often adopt their own criteria for DH and MDA's which are stricter then Federal Regulations.

Other Arrival Procedures

Touch and Go: A training routine involving a touchdown on the runway, full power is applied and a takeoff is made.

Stop and Go: Again for training, except the aircraft is brought to a complete stop before full power is applied for another takeoff.

Go Around: Similar to a missed approach, this command is given if there is an aircraft still on the runway or if the pilot feels unsure of his/her approach.

Low & Over: This procedure is used in situations where there might be a problem with the aircraft. For example, a pilot might have an indication that not all of the landing gear are down and locked. By flying low and over the runway spotters are able to see if the gear are in fact down and thus make a better assessment of the situation.

Introduction | Local Area Control | Departures | ACC - Enroute | FSS | ATC Transcript

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