To be the link between, to ensure IFR aircraft arrival in an orderly sequence, to direct VFR traffic to a position from which it can join the visual circuit without conflictions with IFR traffic, arriving aircraft operating outside con-trolled airspace; at a specified release point - a position, or level agreed on the telephone by the two controllers, the lowest vacant level at the aerodrome’s terminal beacon, to establish an approach sequence in a manner which will facilitate the arrival of the maximum number of aircraft with at least average delay, a reason-able possibility of a successful landing, to rea-lign the aircraft in the correct direction for the descent (a sector
join), to help the pilot lock on the ILS beam by the shortest practicable route,a suitable point on the approach path marked by a radio beacon, to serve as a check point in timing successive ap-proaches; to arrange traffic in line together with the correct spacing, particularly at airports, served by multiple holding stacks, to be authorized to ensure maximum utilization of the arrival runway, to give information by use of the 12 hour clock, due to departing traffic or a previous landing air-craft being slow to clear the RW, too close to traf-fic in front, a reasonable chance of seeing the ap-proach lights and making a successful landing, to request avoiding action, a rapid action required to avoid risk of collision.
B: Read Text “Approach Control” paying attention to the way they are used in the context.
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Text. APPROACH CONTROL
Approach Control is the link between aircraft carries out a missed approach prior to Area and Aerodrome Control, although in becoming visual, it must climb to the safe someparts of the world it may serve a large terrain clearance altitude, in this example -area in the absence of a proper Area Control 3,000ft.
service (Port Vila Approach in Vanuatu, South The decisionheight isthelevelatPacific, for example). It ensures that IFR air- whichthepilotonaprecisionapproachmustcraft arrive in an orderly sequence and that achieve the required visual areference to ilcon-
which it can join the visual circuit without con- tinuetheapproach to a landing. A precision flictions with IFR traffic. Approach will have
the first contact with arriving aircraft operating
outside controlled airspace, and at very rudi- proaches, and SRAs, are non-precision and the drome services will be combined on a single term Minimum Descent Height is used h instead.
(EAT) is often heard at non-radar equipped
airports. This indicates to a pilot that if he Area to Approach at a specified release point, hasaradio failure he must not commence an aposition,or level agreed on the telephone by instrument approach until this specific time to
thetwocontrollers before the aircraft comes allow preceding aircraft to descend and land. ontotheApproach frequency. Area will al- ‘ No delay expected ’ means that a pilot can be-ready have requested the lowest vacant level at ginhisapproach as soon as he reaches the the aerodrome’s terminal beacon and cleared beacon. If his estimate for the beacon is 12, the aircraft to descend accordingly. Ideally, the thenextaircraft’sEATwillbe19,thethird’sarriving aircraft should be released in plenty of 26,and so on. When necessary, EATs are time to enable it carry out a straight-in ap- passed to Area along with the lowest vacant
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proach and simultaneously lose height. How- level in the holding stack – so-called ‘lowest ever, should a busy traffic situation exist, it and earliest’.
might be necessary to put it into the holding completestlet-down eprocedureesand athree d mi-
terns are a standard oval ‘racetrack’ in the di- nuteswillbeadded to this if an aircraft ar-rection of turn and headings being published has to realign itself in the correct direction ICAO’sguidelineistoestablishanapproach for the descent (a sector join). The controller sequence in a manner which will facilitate the
arrival of the maximum number of aircraft with at least average delay. Priority will be giv-
en to aircraft in emergency, hospital flights, Japan.Asuitablepointontheapproach path and certain other specific operations. marked by a radio beacon serves as a check At airfields without radar, traffic is separated pointintimingsuccessiveapproaches. Aircraft
by procedural methods, the first aircraft mak- are given a time at which to pass the speci-ing an instrument approach from, say 3,000 ft, fied point inbound. The time is determined aircraft continuing to hold above 1,000 ft ver- in order to achieve the desired interval between tical intervals. As soon as the first aircraft re- landings on the runway while maintaining mini-ports visual with the ground or approach mum separation at all times, including the lights, and there is a reasonable possibility of a period of runway occupancy.
successful landing, the second aircraft is Where Approach Radar is in use, the
cleared for the approach and so on. If the ACC also transfers radar identity in what is called a handover (a ‘handoff ’ to the Americans).
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The Approach Controller is sure that the aircraft he is directing on his radar display is the correct one. The controller may pass headings (vectors) to the pilot to help him lock on the ILS beam by the shortest practicable route. If there is no ILS, a Surveillance Radar Approach (SRA) will be given or, when the weather is suitable, ra-dar positioning to a visual final.
If a radar directed circuit is flown, the terms downwind, base leg, and final are used where necessary, although the area of sky covered is far bigger than in the normal visual traffic pattern.
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A closing heading of 30° is recom-mended so that when the aircraft inter-cepts the ILS only a gentle turn is neces-sary to lock on. The aim is to intercept the standard 3° glide path at seven to eight miles out on the extended centreline of the runway. At this point the aircraft should be between 2,000 ft and 2,500 ft.
Subsequent landing aircraft are vec-tored not less than five miles behind, or further depending on the vortex wake cat-egory of the preceding traffic. Bigger gaps may also be built in to give space for de-parting traffic at single-runway airports. At certain locations reduction of the separa-tion to three miles is authorized to ensure maximum utilization of the arrival runway. The wake turbulence rules still apply, of course. Great skill is needed to arrange traffic in line together with the correct spacing, particularly at airports, served by multiple holding stacks. Speed control is also used to even out the flow of traffic. The Approach Controller passes an eight mile check to his colleague in the tower who will already have details of the arriv-ing aircraft. If there are no departures at the RW holding point, a landing clearance may be given at this juncture, but it is more useful to give it at the four-mile range. Alternatively, once the pilot reports established on the ILS, Approach may tell him to contact the Tower who will give landing clearance when available.
Pilots expect to receive a landing clear-ance at about four miles on final approach, but this is not always possible due to depart-ing traffic or a previous landing aircraft being slow to clear the RW. Two miles is the ab-solute minimum for large transport aircraft because a go-around is a very important op-eration. The phrase ‘ expect late landing clearance ’ is sometimes heard because light aircraft in a busy circuit may receive it only on very short final. They may even be told to go around if they get too close to traffic in front.
For a runway not equipped with ILS the radar controller is normally able to offer a Surveillance Radar Approach. If the weather is poor this can be down to half a mile touchdown. This ensures a reasonable chance of seeing the approach lights and making a successful landing.
Precision Approach Radar (PAR) is nowadays confined mainly to military ATC but it is still in common use at civil airports in Russia to monitor ILS and other instru-ment approaches. PAR requires two radar dis-plays, one showing the approach centreline in plan view, i.e. from above, and a second showing the glidepath from the side. Height as well as heading corrections can be provided by the controller. Standard phrases include: ‘ This will be a precision monitored ILS approach RW 27 ’; ‘ Rate of descent is good ’; ‘ On glidepath ’; ‘ Slightly (or well) above below) glidepath ’; ‘ Still... metres (or feet) too high (too low) ’; ‘ Coming back slowly to the glidepath ’.