In aeronautics, the final approach (also called the final leg and final approach leg [1] ) is the last leg in an aircraft's approach to landing, when the aircraft is lined up with the runway and descending for landing. [2] In aviation radio terminology, it is often shortened to "final".
In a standard airport landing pattern, which is usually used under visual meteorological conditions (VMC), aircraft turns from base leg to final within one-half to two miles of the airport. For instrument approaches, as well as approaches into a controlled airfield under visual flight rules (VFR), often a "straight-in" final approach is used, where all the other legs are dispensed within. Straight-in approaches are discouraged at non-towered airports in the United States. [3]
An approach slope is the path that an aircraft follows on its final approach to land on a runway. It is ideally a gentle downward slope. A commonly used approach slope is 3° from the horizontal. However, some airports have a steeper approach slope because of topography, buildings, or other considerations. London City Airport, for example, has a 5.5° approach slope; only aircraft that can maintain such an approach slope are allowed to use the airport. [4] In the United Kingdom, any approach of 4.5° or greater is defined as steep and requires special approval. [5] Steeper approaches require a longer landing distance, which reduces runway throughout at busy airports, and requires longer taxi distances. Airports such as Heathrow and London Luton are trialling slightly steeper approaches (3.2°) to reduce noise, by keeping the aircraft higher for longer and reducing engine power required during descent. [6] [7]
United States TERPS (Terminal Instrument Procedures) specifies maximum glidepath angles/vertical descent angles for each aircraft approach category. [8]
The term glide slope is sometimes used to mean approach slope, although in precise usage the glide slope is the vertical guidance element of the instrument landing system. [2]
ICAO operating procures describe the final approach segment as being the segment beginning at the final approach fix/point (FAF/FAP) and ending at the missed approach point (MAPt). [9] The FAF/FAP is generally either a co-located navigational aid beacon (for example a non-directional beacon) or known distance to a beacon (typically located at the aerodrome), which would identify the point for final approach to be commenced by the flying crew. [10] [11] The final approach point (FAP) is an equivalent point for a precision approach, where intermediate approach segment intercepts the glideslope of an instrument landing system. [12]
Under ICAO, The FAF and FAP are two different concepts, representing potentially two different altitude-distance points from the MAPt for different approaches to the same runway. However, the FAF and FAP share the same definition as being the point at which the final approach segment is commenced. [13] For example, the FAF for the VOR+DME approach to Runway 10 at Alicante Airport is at 3600 feet and 9.5nm from the Alicante VOR/DME ("ATE") - whereas the FAP for the ILS approach to Runway 10 at the same airport is at 3300 feet and 9.5nm from the ILS/DME. [14]
Pragmatically, in an aviation world becoming less reliant on traditional navigational aid beacons, the FAF and FAP have come to be known as the same thing - accordingly, approach plates tend to mark the FAF/FAP with same symbol, typically with a cross symbol such as maltese cross or cross potent.
For example, in the United States, the final approach fix is marked on a NACO IAP by a lightning bolt symbol and on a Jeppesen terminal chart by the end of the glide slope path symbol. It is the point in space where the final approach segment begins on an instrument approach. The final approach point is a point on a non-precision approach and is marked by a maltese cross symbol. In the United States, where the approach navigation aid is on the field and there is no symbol depicted, the final approach point is "where the aircraft is established inbound on the final approach course from the procedure turn and where the final approach descent may be commenced". [15]
According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a human-made surface or a natural surface. Runways, taxiways and ramps, are sometimes referred to as "tarmac", though very few runways are built using tarmac. Takeoff and landing areas defined on the surface of water for seaplanes are generally referred to as waterways. Runway lengths are now commonly given in meters worldwide, except in North America where feet are commonly used.
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to approach until it is 200 feet (61 m) over the ground, within a 1⁄2 mile (800 m) of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a missed approach. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe landing can be made. Other versions of the system, or "categories", have further reduced the minimum altitudes, runway visual ranges (RVRs), and transmitter and monitoring configurations designed depending on the normal expected weather patterns and airport safety requirements.
The visual approach slope indicator (VASI) is a system of lights on the side of an airport runway threshold that provides visual descent guidance information during final approach. These lights may be visible from up to 8 kilometres (5.0 mi) during the day and up to 32 kilometres (20 mi) or more at night.
In aviation, an instrument approach or instrument approach procedure (IAP) is a series of predetermined maneuvers for the orderly transfer of an aircraft operating under instrument flight rules from the beginning of the initial approach to a landing, or to a point from which a landing may be made visually. These approaches are approved in the European Union by EASA and the respective country authorities and in the United States by the FAA or the United States Department of Defense for the military. The ICAO defines an instrument approach as "a series of predetermined maneuvers by reference to flight instruments with specific protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if landing is not completed, to a position at which holding or en route obstacle clearance criteria apply."
The microwave landing system (MLS) is an all-weather, precision radio guidance system intended to be installed at large airports to assist aircraft in landing, including 'blind landings'. MLS enables an approaching aircraft to determine when it is aligned with the destination runway and on the correct glidepath for a safe landing. MLS was intended to replace or supplement the instrument landing systems (ILS). MLS has a number of operational advantages over ILS, including a wider selection of channels to avoid interference with nearby installations, excellent performance in all weather, a small "footprint" at the airports, and wide vertical and horizontal "capture" angles that allowed approaches from wider areas around the airport.
Crossair Flight 3597 was a scheduled flight from Berlin Tegel Airport, Germany, to Zürich Airport, Switzerland. On 24 November 2001, the Crossair Avro RJ100 operating the route, registered as HB-IXM, crashed into a wooded range of hills near Bassersdorf and caught fire. Out of the 33 occupants, nine made it out alive.
A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system (ILS), to give pilots a means to determine position along an established route to a destination such as a runway.
A transponder landing system (TLS) is an all-weather, precision landing system that uses existing airborne transponder and instrument landing system (ILS) equipment to create a precision approach at a location where an ILS would normally not be available.
Ansett New Zealand Flight 703 was a scheduled flight from Auckland to Palmerston North. On 9 June 1995, the de Havilland Canada Dash 8-100 aircraft crashed into the Tararua Range on approach to Palmerston North. The flight attendant and three passengers died as a result of the crash; the two pilots and 15 passengers survived.
Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows an aircraft to fly a specific path between two 3D-defined points in space.
Missed approach point is the point prescribed in each instrument approach at which a missed approach procedure shall be executed if the required visual reference does not exist. It defines the point for both precision and non-precision approaches wherein the missed approach segment of an approach procedure begins. A pilot must execute a missed approach if a required visual reference is not in sight upon reaching the MAP or the pilot decides it is unsafe to continue with the approach and landing to the runway. The missed approach point is published in the approach plates and contains instructions for missed approach procedures to be executed at this point.
In aviation, holding is a maneuver designed to delay an aircraft already in flight while keeping it within a specified airspace; i.e. "going in circles."
In aviation, a standard terminal arrival (STAR) is a published flight procedure followed by aircraft on an instrument flight rules (IFR) flight plan just before reaching a destination airport.
TWA Flight 128 was a regularly scheduled Trans World Airlines passenger flight from Los Angeles to Boston, with intermediate stops in Cincinnati and Pittsburgh. On November 20, 1967, Flight 128 crashed on final approach to Greater Cincinnati Airport; 70 of the 82 people aboard the Convair 880 were killed.
Mohawk Airlines Flight 411, a Fairchild FH-227B twin-engine turboprop, registered N7811M, was a scheduled domestic passenger service operated by Mohawk Airlines, between Albany and Glens Falls, New York. On November 19, 1969, it crashed into Pilot Knob Mountain, killing all 14 passengers and crew on board.
A localizer type directional aid (LDA) or Instrument Guidance System (IGS) is a type of localizer-based instrument approach to an airport. It is used in places where, due to terrain and other factors, the localizer antenna array is not aligned with the runway it serves. In these cases, the localizer antenna array may be offset (i.e. pointed or aimed) in such a way that the approach course it projects no longer lies along the extended runway centerline (which is the norm for non-offset and non-LDA localizer systems). If the angle of offset is three degrees or less, the facility is classified as an offset localizer. If the offset angle is greater than three degrees, the facility is classified as a localizer-type directional aid (LDA). Straight-in approaches may be published if the offset angle does not exceed 30 degrees. Only circling minima are published for offset angles greater than 30 degrees. As a "directional aid", and only a Category I (CAT I) approach, rather than a full-fledged instrument landing system (ILS), the LDA is more commonly used to help the pilot safely reach a point near the runway environs, where he or she hopefully can see the runway, at which point he or she will proceed and land visually, as opposed to (for example) full Category III (CAT III) ILS systems that allow a pilot to fly, without visual references, very close to the runway surface (usually about 100 ft) depending on the exact equipment in the aircraft and on the ground.
Muscatine Municipal Airport five miles (8 km) southwest of Muscatine, in Muscatine County, Iowa, United States.
Inex-Adria Aviopromet Flight 450, JP 450, was an international charter flight from Tivat in the Socialist Federal Republic of Yugoslavia to Prague, Czechoslovakia which crashed in the Prague suburb of Suchdol on October 30, 1975, at 09:20 AM. The McDonnell Douglas DC-9-32 with 115 passengers and 5 crew on board descended, under Instrument Meteorological Conditions (IMC), below defined Minimum Descent Altitude (MDA) during the final approach to Prague Ruzyně Airport RWY 25, entered a gorge above Vltava river, and was unable to outclimb the rising terrain. 75 of the 120 occupants died during the crash itself while 4 others died later in hospital. The accident remains the worst aviation disaster on the Czech Republic soil.
Britannia Airways Flight 105 was an international tourist chartered flight from London Luton Airport for a flight to Ljubljana Brnik Airport. Passengers were primarily British, most of them going to their vacation in Yugoslavia. The flight was operated by Bristol 175 Britannia 102 aircraft, registration code G-ANBB. The aircraft took off from Luton at 21:10 hours GMT on August 31, 1966, with 110 passengers and 7 crew on board. After an uneventful en route flight, radar contact was lost at 00:47 hours local time on September 1 during the final approach to runway (RWY) 31. The aircraft struck trees in the woods by the village of Nasovče, 2.8 km south east of the RWY 31 threshold and 0.7 km north of the runway extended centreline, under Visual Meteorological Conditions (VMC). 98 of the 117 passengers and crew were killed in the accident.
Asiana Airlines Flight 162 was a regular short-haul international passenger flight from Incheon International Airport near Seoul, South Korea, to Hiroshima Airport in Hiroshima, Japan. On 14 April 2015, the Airbus A320-232 aircraft touched down short of the runway, struck the localizer array, skidded onto the runway on its tail, and spun 120 degrees before finally coming to a rest on the grass, opposite the terminal building. The aircraft suffered substantial damage to the left wing and engine. Of the 82 people aboard, 27 were injured, one seriously.
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