A critical stage of any flight is the approach since it is the preparation for landing. At this stage, most instrument-rated pilots use GIS (RNAV). Most RNAV approaches are similar to procedures based on ground-based navigation aids like ILS or VOR. Charted feeder routes are included from airways or fixes, each having clearly marked routes and minimum altitudes to fly leading to the last approach segment.
However, some RNAV approaches depend on a different method of handling the transition from the en route environment to the approach, and that system is called Terminal Arrival Areas (TAA).
Discover everything about the Terminal Arrival Area (TAA) by joining us as we share all the details.
What is a terminal approach area?
A terminal approach area is an area that covers controlled airspace around airport landing surfaces where the final approach course after approach clearance takes place. This is often called the Terminal Arrival Area (TAA).
According to the FAA Advanced Avionics Handbook, the Terminal Arrival Area (TAA) is “the published or assigned track by which aircraft are transitioned from the en route structure to the terminal area. A terminal arrival area consists of a designated volume of airspace designed to allow aircraft to proceed direct a protected area with obstacle clearance and signal reception guaranteed where the initial approach course is intercepted.”
Another definition can be found in the FAA Pilot’s Handbook of Aeronautical Knowledge, where it is mentioned that the Terminal Arrival Area (TAA) is “a procedure to provide a new transition method for arriving aircraft equipped with FMS and/or GPS navigational equipment. The TAA contains a “T” structure that normally provides a NoPT for aircraft using the approach.”
Clearly, there is a series of concepts and terms that need to be known to better understand the whole TAA idea. Let’s see some of them.
En route structure
The en route phase of flight is defined as that segment of flight from the termination point of a departure procedure to the origination point of an arrival procedure. The procedures employed in the en route phase of flight are governed by a set of specific flight standards established by Title 14 of the Code of Federal Regulations (14 CFR) [Figure 2-1], Federal Aviation Administration (FAA) Order 8260.3, United States Standard for Terminal Instrument Procedures (TERPS), and related publications. These standards establish courses to be flown, obstacle clearance criteria, minimum altitudes, navigation performance, and communications requirements.
Final approach course
The International Civil Aviation Organization (ICAO) defines the final approach course as “a bearing/radial/track of an instrument approach leading to a runway or an extended runway centerline all without regard to distance.”
Final approach segment
Also, the International Civil Aviation Organization (ICAO) defines the final approach segment as “that segment of an instrument approach procedure in which alignment and descent for landing are accomplished.”
Course reversal makes reference to the maneuvers required to reverse direction and establish the aircraft inbound on an intermediate or final approach course. A course reversal pattern is usually indicated in the Instrument Approach Procedure (IAP) in one of three different ways: a 45°/180° procedure turn, a holding pattern in lieu of procedure turn, or a teardrop procedure.
The maneuver must be completed within the distance and at the minimum altitude specified in the profile view, this usually being the MSA.
What is MSA?
According to ICAO PANS-OPS/I – definitions, MSA stands for Minimum Sector Altitude, which is the lowest altitude which may be used which will provide a minimum clearance of 300 m (1 000 ft) above all objects located in the area contained within a sector of a circle of 46 km (25 NM) radius centered on a radio aid to navigation.
It is important to highlight that MSA is sometimes used to refer to Minimum Safe Altitude, which is a general term used to denote minimum altitude that allows to fly safely in any given area considering the highest terrain or obstacle that may be present in such area. However, this term is not provided by ICAO, so any ICAO document will always refer to Minimum Sector Altitude when using MSA. Therefore, both the pilot and air traffic controller must be careful to establish which term is being referred when using the acronym MSA.
Let’s describe now the three types of course reversal pattern.
This type of course reversal is defined by ICAO as a maneuver in which a turn is made away from a designated track followed by a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of the designated track.
ICAO also provides the following notes:
Note 1: Procedure turns are designated “left” or “right” according to the direction of the initial turn.
Note 2: Procedure turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual approach procedure.
The absence of the procedure turn barbed arrow in the plan view indicates that a procedure turn is not authorized for that procedure. A maximum procedure turn speed of not greater than 200 knots indicated airspeed (KIAS) should be observed when turning outbound over the IAF and throughout the procedure turn maneuver to ensure staying within the obstruction clearance area.
Descent below the procedure turn altitude begins after the aircraft is established on the inbound course.
Holding pattern in lieu of procedure turn
This other course reversal type is defined as a required maneuver (the same as a procedure turn) unless the aircraft is being radar vectored to the final approach course, when “NoPT” is shown on the approach chart, or when the pilot requests or the controller advises the pilot to make a “straight-in” approach.
A hold-in-lieu of procedure turn shall be established over a final or intermediate fix when an approach can be made from a properly aligned holding pattern. The hold-in-lieu of procedure turn permits the pilot to align with the final or intermediate segment of the approach and/or descend in the holding pattern to an altitude that will permit a normal descent to the final approach fix altitude.
The teardrop procedure consists of departure from an IAF on the published outbound course followed by a turn toward and intercepting the inbound course at or prior to the intermediate fix or point. Its purpose is to permit an aircraft to reverse direction and lose considerable altitude within reasonably limited airspace. Where no fix is available to mark the beginning of the intermediate segment, it shall be assumed to commence at a point 10 NM prior to the FAF. When the facility is located on the airport, an aircraft is considered to be on final approach upon completion of the penetration turn. However, the final approach segment begins on the final approach course with the normal procedure turn distance of 10 NM from the facility.
This course reversal is a required procedure unless Air Traffic Control authorizes the opposite.
The profile view
Profiles show how the procedure was described from an angle and show vertical path altitude, directions, distance and fix. The views include the maximum and minimum elevations of procedure turns, altitudes on prescribed fixes, distances from fixings, and the missed approach point and procedure. The profiles view helps pilot interpret the Instrument Approach Procedures (IAP). Profiles are not scale oriented. GPS interceptor elevation is an altitude that is required to provide accuracy of approach glideslope intercepts, this is illustrated by an altitude number and line of “zigzags” in the view.
Airport sketch or Airport diagram
Before flying a plane, the flight crew must examine the layout of the airfields and any alternative routes for which it will land, including those with auxiliary runways for landing operations. As part of flight preparation, examine taxi procedures for departure airports and arrival airports. The expected taxi path should be compared with the taxi chart or the flight diagram, and especially attention should be paid to the specifics or complex intersections along the taxi route. approach clearance
TAA is normally used for the term giving a title to this guide, but it is also used for the term Terminal Arrival Altitude (TAA) which is the same as the MSA. In other words, it is the lowest altitude that will provide a minimum clearance of 300 m (1 000 ft) above all objects located in an arc in a circle defined by an arc of a 46 km (25 NM) radius.
In summary, the TAA (referring to the area) provides a seamless and efficient transition from the en route structure direct to the terminal environment to an underlying RNAV instrument approach procedure for FMS and/or GPS equipped aircraft.
Minimum altitudes depict standard obstacle clearances compatible with the associated instrument approach procedure. TAAs will not be found on all RNAV procedures, particularly in areas with a heavy concentration of air traffic.
When the TAA is published, it replaces the MSA for that approach procedure. A standard racetrack holding pattern may be provided at the center IAF, and if present may be necessary for course reversal and for altitude adjustment for entry into the procedure.
In the latter case, the pattern provides an extended distance for the descent as required by the procedure. The published procedure will be annotated to indicate when the course reversal is not necessary when flying within a particular TAA (e.g., “NoPT”).
Otherwise, the pilot is expected to execute the course reversal under the provisions of 14 CFR Section 91.175 (USA). The pilot may elect to use the course reversal pattern when it is not required by the procedure, but must inform air traffic control and receive clearance to do so.
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A mechanical engineer and aviation enthusiast dedicated to share some knowledge by creating top-notch content, especially in engineering and aviation topics.
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