The aim of any instrument approach is to allow the aircraft to safely descend to a low altitude in order to become visual.

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Brice Powers
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1 INSTRUMENT APPROACH CHARTS "An instrument approach is just a series of straight lines joined by rate one turns" Ron Magrath The aim of any instrument approach is to allow the aircraft to safely descend to a low altitude in order to become visual. There are 2 types of instrument approaches: 1. Precision Approaches 2. Non Precision Approaches In Australia the Instrument Procedures are published by Airservices Australia in the form of the DAP's (Departure and Approach Procedures). Jeppesen also produce these charts in their own format. OLD / NEW Charts Australian IAL charts are designed to two different editions of the ICAO Pans Ops Document. Those designed using the 1971 edition are referred to as OLD CHARTS, those designed to the 1986 edition are called NEW CHARTS. As a result of this there are differences in the rules that apply when conducting these instrument approaches. As a general guide the procedures that apply to NEW charts are found in the AIP DAP section. Information on OLD charts in contained in the front of the DAP's. Differences between OLD and NEW charts One of the obvious differences is that NEW charts cater for Aircraft Category (AIP ENR 1.5 (1.2), next page). This is the easiest way of differentiating between OLD and NEW Charts. DAP page 1-3 shows a table of differences between OLD and NEW charts. DAP 1.9 (page 1-3) Information in the preamble to AIP/IAL conforms to the new criteria. Operational differences between the two types of instrument approach charts are summarised in the following table: Visual Manoeuvring (Circling) area Visual Manoeuvring (Circling) obstacle clearance. Approach Speed and Descent Limitations Minima OLD CRITERIA CHARTS The area contained within 3nm of the ARP except where the aerodrome has runways in excess of 1800m when the circling area is bounded by the circumference of 3nm arcs drawn from the ends of the runways and tangents joining these arcs. Circling minima provide obstacle clearance of at least 400 IAS during approach shall not exceed 175 kts. All altitudes shown on the approach profiles are descent limitations. Charts show day and night minima, but with effect from 22 OCT 1987 the night NEW CRITERIA CHARTS Radius determined by the aircraft category. Circling minima provide obstacle clearance of 300 for Cat A & B aircraft and 400 for Cat C & D. Approach speed limitations are as shown in AIP DAP IAL- 4 table 1.1. Altitude restrictions are as shown in the chart legend at DAP IAL 0-3 and 4. Charts show minima according to aircraft category. DA must be

2 Missed Approach minima are cancelled. The day minima then also apply to night operations (except where night IFR operations are not permitted). Missed approach point not shown on all charts. Missed approach shall be executed on reaching the published position or altitude from which the missed approach commences. Missed approach acceleration segment is not assessed corrected for position error in accordance with AIP DAP ENR 1.5 (1.14.1). DH and RH are radio altimeter readings. Missed approach point shown on all charts. APPROACH TYPES Precision Approach A precision approach provides both Azimuth and glide path information. Currently the Instrument Landing System (ILS) is the only precision approach available to operators in Australia. ILS Approach AIP ENR 1.5 (7) Failures: Locator. In the event of a Locator failure, aircraft must join the ILS outside the outer marker as directed by NOTAM or ATC. Glide Path. In the event of a Glide path failure, only the localizer approach is available. Markers. Where marker beacons are not available, aircraft may use the ILS provided that the alternate fixes nominated on the IAL chart or by NOTAM are used for altimeter checks. Altimeter Checks If the altimeter over reads at the fix (OM) the difference must be added to the DA ILS Minima AIP ENR 1.5(8) Visibility 1.5 km required if HIAL is not available. Visibility 1.2 km required if HIAL is available and the ILS is NOT flown using a flight director or an autopilot coupled to the LLZ/GP or HIRL is unserviceable. Visibility 0.8 km is available to aircraft manually flown with a flight director or an autopilot coupled to the LLZ/GP and a serviceable AI/DI warning system and HIRL is available Note: for most GA aircraft (C310 Baron etc) the visibility required is 1.2km, as most of these aircraft do not have coupled autopilots or flight directors. Check the flight Manual. Pressure Correction AIP ENR 1.5 (1.18.2) If aircraft is tested for PEC you must add this amount to the ILS DA. The details are located in the aircraft flight manual. If the aircraft is not tested for PEC, 50 must be added to ILS DA.

3 Non Precision Approach An Instrument approach and landing that does not utilise electronic glidepath information. HIAL AIP ENR 1.5 (5.4) If HIAL has failed or is not available add 900m to visibility required for runway approaches that normally have HIAL associated with them. (Except for ILS) QNH Sources AIP ENR 1.5 (5.3.2) If the minima boxes are shaded the minima s can be reduced by 100 if the actual QNH is known (ATIS, ATS, AWIB) If a forecast AREA QNH is being used you must ADD 50 to the MDA. Descent During Approach AIP ENR 1.5 (1.16) For the outbound descen the aircraft must be on the specified track OR on a heading to intercept the outbound track before the outbound descent can be commenced. For the final inbound descent or the descent past the FAF the aircraft must be established on the specified track. Established means ½ scale for VOR or ILS and ±5º for the NDB or within ± 2nm for DME arc (AIP ENR 1.5 ( note)) Performance Categories AIP ENR 1.5 (1.2) Aircraft Category A Vat Range To 90 KIAS Example B KIAS C KIAS D KIAS Vat - Speed at threshold based on 1.3 times the stall speed in the landing configuration at maximum landing weight

4 APPROACH REQUIREMENTS Maximum Bank Angle AIP ENR 1.5 (1.18) 25º AOB or Rate one which ever is less. Wind Effect AIP ENR 1.5 (1.17) Allowance needs to be made for the effect of wind in BOTH HEADING AND TIMING. Descent during the Approach AIP ENR 1.5 (1.15/1.16) Descent Gradients SEGMENT GRADIENT NORMAL MAXIMUM Arrival As Required As Required Initial 4 % 8 % Intermediate Level 5 % Final - non precision 5.2% 6.5 % - precision 3 degrees Not applicable TABLE 1.2 For the final descent to the minima associated with an instrument approach the aircraft must be "established" on the inbound track. Established is defined as +/- 5º for NDB, ½ full scale deflection for VOR or ILS or +/- 2nm for DME arc. For instrument approaches with a reversal procedure that specifies an outbound descent, the aircraft must be on the specified track or on an intercept heading to regain the outbound track. Speed Limitations AIP ENR 1.5 (1.10 TABLE 1.1) For OLD charts the maximum IAS in any part of the approach is 175kt. DAP page 1-3 For NEW criteria charts refer to the following table SPEEDS FOR PROCEDURE IN KNOTS IAS Range of Range of Max Speeds for ACFT Category Vat Speeds for Final Visual Max Speeds for Initial Approach Manoeuvring Missed Approach Approach Speeds (Circling) A <91 90/150 70/ (110*) B 91/ /180 85/ (140) C 121/ / / D 141/ / / E 185/ / / TABLE 1.1 * Maximum speed for reversal procedures

5 VISUAL CIRCLING AIP ENR 1.5 (1.6) After the completion of an instrument approach that is not aligned with a runway visual circling will be required. The requirements of visual circling are contained in AIP ENR 1.5 (1.6) Visual Circling is very different from a Visual Approach and care should be taken not to confuse the rules and procedures that apply to each. During visual circling it may be necessary to descend below the MDA. You may do this provided the requirements of AIP ENR 1.5 (1.6.3) are adhered to. Rules for Visual Circling Descent below MDA AIP ENR 1.5 (1.6.3) During Visual Circling, descent below the MDA may only occur when the pilot: a. maintains the aircraft within the circling area; and b. maintains a visibility, along the intended flight path, not less than the minimum specified for circling; and c. maintains visual contact with the landing runway or approach lights or other markings associated with the approach end of the runway; and either d. at an altitude not less than MDA intercepts a position on the downwind, base or final leg of the traffic pattern, and, from this position can complete a continuous descent to the landing threshold FIG 1 e. in daylight only maintains visual contact with the obstacles along the intended flight path and an obstacle clearance not less than the minimum for the aircraft performance category until the aircraft is aligned with the landing runway.

Radii are: Cat A Cat B Cat C Cat D Cat E 1.68 nm 2.66 nm 4.20 nm 5.28 nm 6.

6 Circling Area AIP ENR 1.5 (1.6.3) note 1 NEW CHARTS The circling are is determined by drawing an arc centred on the threshold of each useable runway and joining these arcs by tangents. Radii are: Cat A Cat B Cat C Cat D Cat E 1.68 nm 2.66 nm 4.20 nm 5.28 nm 6.94 nm OLD CHARTS The area contained within 3nm of the ARP has runways in excess of 1800m when the the circumference of 3nm arcs drawn from tangents joining these arcs except where the aerodrome circling area is bounded by the ends of the runways and Obstacle clearance AIP ENR 1.5 (1.6.3) note 2 New Charts Cat A&B 300 Cat C&D 400 Cat E 500 Old Charts All aircraft 400

AERODROME OPERATING MINIMA

Title: Determination of Aerodrome Operating Minima Page 1 of 8 AERODROME OPERATING MINIMA 1. PURPOSE 1.1 The purpose of this Advisory Circular is to provide methods to be adopted by operators in determining