Manual of Standards Part 173—Standards Applicable to Instrument Flight Procedure Design
(c) Obstacles.(c) Obstacles.
Start here
Get a plain-English read of (c) Obstacles.
Turn the raw legal text into a practical explanation grounded in Manual of Standards Part 173—Standards Applicable to Instrument Flight Procedure Design.
8.1.1.1 Performance Category Groups. Procedures should normally be designed for category groups. Common grouping is A/B and C/D. Unless specific operational gain is necessary, groups must not be split for OCA penalties of less than 100 ft.
8.1.1.2 Category E. Category E procedures will not normally be designed.
8.1.1.3 Overlapping Procedures. The primary areas for instrument approach procedures other than DME Arrivals must not be closer than one nautical mile to the primary area of a procedure to a second aerodrome, unless all procedures involved are wholly contained in controlled airspace. Where this is not practical, vertical separation may be used to ensure that a minimum of 1,000 ft is maintained between aircraft on the two procedures.
8.1.1.4 Airspace Buffers. Procedures within controlled airspace must be designed so that:
(a) horizontally:
(i) a 1 NM buffer is provided between the airspace boundary and the boundary of:
(A) for holding—the primary holding area;
(B) for non-precision approach segments—the primary area;
(C) for precision approach segments—the OAS W and X surfaces.
(b) vertically:
(i) A 500 ft buffer is provided between the nominal aircraft position and an airspace boundary set for VFR level; or
(ii) A 1,000 ft buffer is provided between the nominal aircraft position and an airspace boundary set at a useable IFR level;
except for precision approaches where, in addition, the basic ILS surfaces must be wholly contained within the controlled airspace boundary;
(c) for the Missed Approach Segment:
(i) clearance from airspace is determined using a combination of vertical and horizontal dimensions:
(A) vertically, the height of the nominal aircraft position in a missed approach is determined by applying the techniques of PANS-OPS Vol II, or ICAO Doc 9905 missed approach criteria, using a gradient of 5% from the SOC to the missed approach altitude;
(B) if this height conflicts with airspace, then horizontally a 1 NM buffer is provided between the airspace boundary and the missed approach primary area.
Note: If airspace considerations require a nominal gradient greater than 5%, the IAL chart must show a climb gradient identified by an asterisk.
8.1.1.5 Prohibited and Restricted (P and R) Areas. Procedures which cross or abut P and R areas must be designed so that:
(a) where the P or R area contains flying activities:
(i) horizontally, the boundary of the P or R area does not infringe:
Section (c) Obstacles. - Manual of Standards Part 173—Standards Applicable to Instrument Flight Procedure Design - (c) Obstacles. | Zoe
(A) for holding—the primary holding area plus a 1 NM buffer;
(B) for non-precision approach segments:
the primary area of Initial and Intermediate Approach segments plus a 1 NM buffer, and
the primary and secondary area of the Final Approach segment;
(C) for precision approach segments—the OAS W and X surfaces plus a 1 NM buffer.
(ii) vertically, the altitude limit over the area must be the vertical limit of the P or R area plus 500 ft, or the altitude dictated by obstacle clearance criteria, if higher.
(b) where the P or R area is not used for flying activities:
(i) horizontally, the boundary of the P or R area must not infringe:
(A) for holding—the primary holding area;
(B) for non-precision approach segments—the primary area of the Initial, Intermediate and Final approach segments;
(C) for precision approach segments—the OAS W and X surfaces;
(ii) vertically, the upper limit of the P or R area may be used provided obstacle clearance criteria are met.
(iii) for the Missed Approach Segment, clearance from airspace is determined using a combination of vertical and horizontal dimensions:
(A) vertically, the height of the nominal aircraft position in a missed approach is determined by applying the techniques of PANS‑OPS Vol II, or ICAO Doc 9905 missed approach criteria, using a gradient of 5% from the SOC to the missed approach altitude;
(B) if this height conflicts with a P or R area, then horizontally the missed approach primary and secondary areas must not infringe the P or R area boundary.
Note: If a gradient of greater than 5% is required, the IAL chart must show the climb gradient identified by an asterisk.
8.1.1.6 Danger Area Associated with High-Velocity Gas Efflux. Procedures which cross or abut danger areas associated with high-velocity gas efflux must be designed so that:
(a) for procedures based on conventional navigation aids:
(i) horizontally, the danger area does not infringe the procedure primary area.
(ii) vertically, the upper limit of the danger area may be used provided obstacle clearance requirements are met.
(b) for GPS based procedures:
(i) horizontally, the nominal final approach and missed approach tracks clear the danger area by a minimum of 1,000 m;
(ii) vertically, the upper limit of the danger area may be used provided obstacle clearance criteria are met;
(iii) the missed approach incorporates a minimum turn of 45° away from the danger area.
8.1.2 Procedure Identification
8.1.2.1 Instrument procedure charts must be identified in accordance with ICAO Annex 4 requirements.
8.1.3.1 Wherever possible, non-precision approach procedures must be designed as straight-in approaches in accordance with the alignment criteria contained in PANS‑OPS Vol II or ICAO Doc 9905 for RNP AR APCH.
8.1.3.2 Publication of straight-in minima is limited to aerodromes where the runway conforms to the Non-Precision Approach Runway standards contained in MOS Part 139, with the following exceptions for GPS non-precision approach procedures.
(a) Runway Width and Strip Width. Minimum runway width of 30 m and a minimum strip width of 90 m for procedures limited to code 1, 2 and 3C aeroplanes. For aerodromes with a runway strip width less than 300 m, the MDA must be adjusted in accordance with paragraph 8.1.4.1. Runways accommodating aeroplanes above code 3C require a minimum graded runway strip width in accordance with MOS Part 139.
(b) Approach OLS Area and Gradient. The approach OLS area and gradient parameters are as per MOS Part 139, except that the length of inner edge may be reduced to a minimum length equal to the runway strip width provided in accordance with paragraph 8.1.3.2(a). Where an OLS area survey to the Non-Precision Approach Runway criteria is not available, a straight-in approach minima may be published, provided the MDA is 500ft or more above the aerodrome elevation and an operational assessment confirms the visual approach path is clear of obstacles. The visual approach path for these purposes commences at the point where the nominal 3° approach path coincides with the planned MDA. The obstacle free plane extends from this “Nominal Intercept Point” at an altitude equal to the MDA minus MOC, to a point 50 ft above the runway threshold. (See Figure 8‑1). Laterally, the visual approach path will commence with a width equal to the runway strip width provided and splay at 10% to the visual approach point described above.
Visual descent segment
Figure 8‑1: Visual descent segment
(c) Surface Wind Information. Surface wind information must be provided in accordance with CAO 92.2.
(d) Runway Edge Lighting. Runway edge lighting shall have 60 m spacing, except that existing 90 m spacing is acceptable subject to assessment for Non-Precision Approach Runways intended to be used in visibility conditions of 1.5 km or more. The suitability of existing 90 m spaced lighting for night approaches must be assessed during the instrument approach validation process.
8.1.4 Visual Segment Limitations
8.1.4.1 Runway Strip Width less than 300 Metres. Where a straight-in procedure is approved to a runway with a runway strip width of less then 300 m, the minimum obstacle clearance height (OCH) for straight-in procedures required must be no lower than the final segment minimum obstacle clearance plus
Formula — runway strip width less than 300 metres and the minimum obstacle clearance height for straight-in procedures. metres
Note: The minimum OCH for straight-in procedures referred to in paragraph 8.1.4.1 is as follows:
Note: (a) Precision:
Note: As determined by OAS or CRM
Note: (b) Non-precision (without FAF - 295 ft MOC):
Note: Runway Strip Width (m) Minimum OCH (ft)
Note: 230 311
Note: 180 323
Note: 150 330
Note: 90 344
Note: (c) Non-precision (with FAF - 246 ft MOC):
Note: Runway Strip Width (m) Minimum OCH (ft)
Note: 230 262
Note: 180 274
Note: 150 281
Note: 90 295
8.1.4.2 Parallel Runways—Sidestep Procedures. Sidestep procedures shall have a visual segment ceiling not less than that derived from the following formula:
Formula — Parallel Runways – Sidestep Procedures. 318.4 + F
Where VS = visual segment ceiling (feet)
X = ceiling for final segment C/L intercept of 30°
Values are:
CAT A: 300
CAT B: 330
CAT C: 435
CAT D: 540
D = distance between parallel runways in nautical miles
F = factor; for CAT A: 48; CAT B: 82; CAT C: 118; CAT D: 153.
(above values are in feet)
8.1.5 OCA and Descent Limits
8.1.5.1 In addition to the requirements of PANS‑OPS Vol II or ICAO Doc 9905 for RNP AR APCH, the following factors are to be taken into account in determining OCA:
(a) Accuracy of Maps and Charts. The vertical and horizontal accuracy of the maps and charts used during instrument approach procedure design must be accounted for. In particular:
(i) if the vertical accuracy of the map or chart cannot be determined a value of ± 10 m must be used;
(ii) if terrain height is being determined from contour information, the height of the highest terrain must be assumed to be the height of the highest contour plus the contour interval of the map;
(iii) spot height information does not attract any accuracy superior to that of contour information—therefore, despite the presence of spot height information, terrain height must be calculated from contour data in accordance with paragraphs 8.1.5.1(a)(i) and 8.1.5.1(a)(ii) above.
(iv) survey control point information and the elevation of the top of some structures are subject to specific survey—therefore, these heights may be used without adding the map/chart vertical accuracy described in this sub-paragraph.
(b) Forecast Altimeter Setting Error.
(i) at aerodromes where a 24-hour ATC tower service is not provided, and a TAF is issued on a 24-hour basis (TAF Category 1 or 2 aerodrome), an allowance of 100 ft (3 hPA) must be added to the lowest OCA;
(ii) for aerodromes where a TAF may not be available 24 hours per day, an allowance of 150 ft (5 hPA) must be added to the lowest OCA;
(iii) the published MDA box will be shaded in both cases to permit a reduction of 100 ft to MDA if local QNH is available from an approved source.
(c) Obstacles.
(i) all known obstacles, including vegetation, must be accounted for. In addition, an allowance must be made for vegetation growth and the erection of new obstacles in the period between obstacle surveys. The allowance for these factors must be 100 ft over open country or water suitable only for leisure boating and 200 ft over tropical rain forest, open water, or built-up areas. In the event of known obstacles exceeding these values, the greater value must be used.
8.1.6 Visibility
8.1.6.1 Definitions. In paragraphs 8.1.6.1A to 8.1.6.1D:
APLL, in relation to a runway, means:
(a) the length of an ALS, for the runway, in metres; or
(b) if there is NALS in relation to the runway — zero metres.
MDH means minimum descent height.
straight-in approach procedure aligned with runway centreline means a straight-in approach procedure, for a runway, which:
(a) utilises precision approach (ILS or GLS), ILS localiser, GNSS, VOR, or NDB, guidance for the final approach segment, and
(b) for which the final approach track is offset by:
(i) for a Cat A or B aeroplane — not more than 10 degrees from the runway centreline; or
(ii) for a Cat C or D aeroplane — not more than 5 degrees from the runway centreline.
TCH means threshold crossing height.
VPA means vertical path angle, in degrees.
8.1.6.1A Application of procedures for determining minimum RVR, or visibility, for certain straight-in approach procedures. The procedures for determining minimum RVR, or visibility, under paragraphs 8.1.6.1B and 8.1.6.1C apply to any of the following straight-in approach procedures:
(a) a precision approach procedure with a DH of not less than 200 ft;
(b) an approach procedure with vertical guidance;
(c) a non-precision approach procedure;
which meets the PANS-OPS Vol II, or ICAO Doc 9905, requirements for a straight-in approach procedure.
8.1.6.1B Method for determining minimum RVR or visibility — straight-in approach procedure aligned with runway centreline. Subject to paragraph 8.1.6.1D, for a straight-in approach procedure mentioned in paragraph 8.1.6.1A, which is a straight-in approach procedure aligned with runway centreline, the minimum RVR, or visibility, for the procedure is the greater of the following:
(a) Image unavailable in extracted text;
(b) the value, as an RVR or visibility, stated in column 1, 2, 3 or 4 of Table 8.1, relevant to the type of ALS in relation to a runway stated in the first row of the table.
8.1.6.1C Method for determining minimum RVR or visibility — other straight-in procedures. Subject to paragraph 8.1.6.1D, for a straight-in approach procedure mentioned in paragraph 8.1.6.1A, which is not a straight-in approach procedure aligned with runway centreline, the minimum RVR, or visibility, for the procedure is the greater of the following:
(a) Image unavailable in extracted text;
(b) 1 500 m.
8.1.6.1D Use of RVR minimum. For paragraphs 8.1.6.1B and 8.1.6.1C, an RVR minimum may be used only for a procedure to approach a runway equipped with electronic RVR measuring equipment.
8.1.6.2 Maximum RVR or visibility. For a straight-in approach procedure, the maximum RVR, or visibility, for the procedure is 5 km.
8.1.6.2A Minimum Values for Precision Approach Category II and III procedures. For an approach type mentioned in column 1 of Table 8-1A, the minimum RVR values approved for precision approach Category II or III procedures are those in column 2 of the Table which, subject to the runway capability conditions mentioned in column 3 of the Table, correspond to the approach type.
Table 8-1A: Category II and III minimum visibility based on runway capability
<table cellspacing="0" cellpadding="0" style="margin-left:56.45pt; border:0.75pt solid #000000; border-collapse:collapse"><thead><tr><td style="border-right:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt; vertical-align:top"><p class="TableHeading" style="margin-bottom:6pt"><span>Approach type (Column</span><span> </span><span>1)</span></p></td><td style="border-right:0.75pt solid #000000; border-left:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt; vertical-align:top"><p style="text-align:center; line-height:115%"><span style="font-weight:bold">Minimum RVR (metres)</span></p><p class="TableHeading" style="margin-bottom:6pt"><span>(Column 2)</span></p></td><td style="border-left:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt; vertical-align:top"><p style="text-align:center; line-height:115%"><span style="font-weight:bold">Runway capability</span></p><p class="TableHeading" style="margin-bottom:6pt"><span>(Column 3)</span></p></td></tr></thead><tbody><tr><td rowspan="2" style="border-top:0.75pt solid #000000; border-right:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p class="TableHeading" style="margin-top:3pt; margin-bottom:3pt; text-align:left"><span>Precision approach Category II</span></p></td><td style="border:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p style="page-break-after:avoid"><span>350</span></p></td><td style="border-top:0.75pt solid #000000; border-left:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>Precision approach runway Category</span><span> </span><span>II.</span></p><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>Precision approach Category II and III lighting system.</span></p><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>Touchdown Zone (TDZ) RVR sensor and at least 1 RVR sensor at either the MID point or END zone.</span></p></td></tr><tr><td style="border:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p><span>300</span></p></td><td style="border-top:0.75pt solid #000000; border-left:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>In addition to the runway capability requirements for operations with a minimum RVR of 350</span><span> </span><span>m, the runway has:</span></p><p style="margin-top:3pt; margin-left:35.45pt; margin-bottom:3pt; text-indent:-35.45pt"><span>(a)</span><span style="width:20.78pt; text-indent:0pt; display:inline-block"> </span><span>runway centreline lighting with a longitudinal spacing that applies to a runway intended for use in RVR conditions less than a value of 350</span><span> </span><span>m; and</span></p><p style="margin-top:3pt; margin-left:35.45pt; margin-bottom:3pt; text-indent:-35.45pt; page-break-after:avoid"><span>(b)</span><span style="width:20.78pt; text-indent:0pt; display:inline-block"> </span><span>either:</span></p><p style="margin-top:3pt; margin-left:70.9pt; margin-bottom:3pt; text-indent:-35.45pt"><span>(i)</span><span style="width:24.79pt; text-indent:0pt; display:inline-block"> </span><span>an ILS classified at least II/D/2; or</span></p><p style="margin-top:3pt; margin-left:70.9pt; margin-bottom:3pt; text-indent:-35.45pt"><span>(ii)</span><span style="width:22.13pt; text-indent:0pt; display:inline-block"> </span><span>taking into account any associated operating limitation, a precision approach facility that has performance characteristics at least equivalent to an ILS classified at least II/D/2.</span></p></td></tr><tr><td style="border-top:0.75pt solid #000000; border-right:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p class="TableHeading" style="margin-top:3pt; margin-bottom:3pt; text-align:left"><span>Precision approach Category IIIA</span></p></td><td style="border:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p style="page-break-after:avoid"><span>175</span></p></td><td rowspan="2" style="border-top:0.75pt solid #000000; border-left:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>Precision approach runway Category</span><span> </span><span>III.</span></p><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>Precision approach Category II and III lighting system.</span></p><p style="margin-top:3pt; margin-bottom:3pt; page-break-after:avoid"><span>RVR sensors at all zones.</span></p></td></tr><tr style="height:47pt"><td style="border-top:0.75pt solid #000000; border-right:0.75pt solid #000000; border-bottom:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p class="TableHeading" style="margin-top:3pt; margin-bottom:3pt; text-align:left; page-break-after:auto"><span>Precision approach Category IIIB</span></p></td><td style="border:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p><span>75</span></p></td></tr><tr><td style="border-top:0.75pt solid #000000; border-right:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p class="TableHeading" style="margin-top:3pt; margin-bottom:3pt; text-align:left; page-break-after:auto"><span>Precision approach Category IIIC</span></p></td><td colspan="2" style="border-top:0.75pt solid #000000; border-left:0.75pt solid #000000; padding-right:5.03pt; padding-left:5.03pt"><p><span>Not applicable in the Australian environment.</span></p></td></tr></tbody></table>
Note: Visibility values for Special Authorisation Category I procedures and Special Authorisation Category II procedures are stated at paragraphs 8.1.14 and 8.1.15.
8.1.6.3 Circling. Circling visibility must be determined from Table 8-2. (The basis upon which the values for circling visibility have been determined are contained in Table 8-2A.)
Table 8‑2: Circling visibility
Aircraft Category
A
B
C
D
E
Circling Visibility (km)
2.0
2.4
4.00
5.00
7.00
Note: The values in Table 8-2 have been determined allowing for an omni directional wind of 25 knots, an achieved bank angle of 25°, an OAT of ISA + 15, an altitude of aerodrome elevation plus 1,000 ft and the average visual manoeuvring speed for the aircraft category. Subject to an absolute minimum value of 2 km, the values were derived using the following formula:
Note: V = 0.9D
Note: Where V = circling visibility
Note: D = diameter of turn at the average manoeuvring speed for category
Note: 0.9 = minimum downwind spacing, in nautical miles, to achieve alignment on final approach.
Note: The circling visibility recognises that the pilot of the aircraft must be able to see the runway from the downwind position.
Table 8-2A: Circling visibility values
Category
A
B
C
D
IAS (kt)
90.00
125.00
170.00
195.00
TAS (1 000 ft, ISA + 15)
93.70
130.14
176.99
203.01
r (km)
0.51
0.98
1.81
2.38
E (km)
0.21
0.29
0.39
0.45
D=2r +2E
1.43
2.54
4.41
5.67
0.9D
1.29
2.29
3.97
5.11
Minimum Circling Visibility
2.00
2.40
4.00
5.00
8.1.6.4 Where a procedure terminates outside the circling area, a visual segment may be provided. The visibility for a visual segment must be 5,000 m.
8.1.7 State Minima
8.1.7.1 Visibility. The State visibility minima must be the value determined by paragraph 8.1.6, adjusted as follows:
(a) for RVR values up to 400 m, the calculated values must be rounded-up to the nearest multiple of 25 m;
(aa) for RVR values greater than 400 m and up to 800 m, the calculated values must be rounded-up to the nearest multiple of 50 m;
(b) for RVR values greater than 800 m and visibility values up to 1,000 m the calculated values must be rounded-up to the nearest multiple of 100 m;
(c) for visibility values greater than 1,000 m, the calculated value must be rounded-up to the nearest multiple of 200 m.
Exception. For runway approaches it must not be less than the minimum values permitted at paragraphs 8.1.6.1B, 8.1.6.1C, 8.1.6.2A, 8.1.14 and 8.1.15.
Note: The rounding in paragraph 8.1.7.1 may give inappropriate values when determining visibility for foreign procedures. In such cases, the value determined under paragraph 8.1.6 may be rounded to any value within the following range:
Note: 1. for RVR values up to 800 m = 25 m;
Note: 2. for RVR values greater than 800 m = 50 m;
Note: 3. for visibility values greater than 1,000 = 100 m
8.1.7.2 DA/MDA. The State DA/MDA must not be less than any of the following:
(a) the OCA determined in accordance with ICAO PANS‑OPS Vol II or ICAO Doc 9905 for RNP AR APCH and paragraph 8.1.5;
(b) the visual segment limitations contained in paragraph 8.1.4;
(c) the OCA plus any margin deemed necessary to account for poor ground equipment performance or local conditions;
(d) for Category I operations — threshold elevation plus 200 ft;
(e) for SA Category I operations — threshold elevation plus 150 ft;
(f) for Category II and SA Category II operations — threshold elevation plus 100 ft.
8.1.7.3 RA Height. A radio altimeter (RA) height must be determined and published for each SA Category I, SA Category II and Category II instrument flight procedure.
Note: A DH or RA height is not required for Category III procedures. If an operator’s approval requires use of a DH for a particular Category III operation, the flight crew will apply the DH specified in the approval.
8.1.8 Aerodrome Operating Minima (AOM)
8.1.8.1 AOM must be the higher of the OCA corrected for the factors listed in ICAO Annex 6 or the State DA/MDA. For precision approaches, the State DA must be adjusted for pressure error to determine the AOM. Aircraft pressure error correction must be applied or, alternatively, at least 50 ft added to the DA.
8.1.9 General Alternate Minima
8.1.9.1 The general alternate minima must be calculated by adding the tolerance for the forecast ceiling and visibility to the circling minima (500 ft and 2 km).
8.1.10 Special Alternate Minima
8.1.10.1 Airborne Equipment. Special Alternate Minima are available only for operations by aircraft with dual ILS/VOR navigation capability (that is, with duplicated LLZ, G/P, Marker and VOR receivers). Although not specified and not required, it is assumed that such aircraft will also have duplicated ADF systems.
8.1.10.2 Ground Equipment. For a location to be considered it must be served by ILS, LLZ or straight in VOR instrument approach procedures to at least two runway directions which are suitable for use by all aircraft likely to use the special low alternate minima.
8.1.10.3 The instrument approach procedures should preferably utilise different VHF ground equipment. However, the use of the same ground equipment for both approaches is acceptable provided the equipment meets the requirements of ICAO Annex 10, Volume 1, Attachment C, Table C2 or Attachment F, as applicable, and an alternative straight in instrument approach procedure which utilises a different aid is available.
8.1.10.4 Other Requirements. Only controlled aerodromes qualify. The Special Alternate Minima shall not be available during any period when ATC and Bureau of Meteorology (BoM) observations and forecasting services are not provided at the aerodrome concerned.
8.1.10.5 Calculation of Special Alternate Minima. To calculate Special Alternate Minima:
(a) add 500 ft ceiling and 1.5 km visibility to the ceiling and visibility minima of the VHF runway aligned instrument approach procedure which provides the greatest advantage.
(b) add 400 ft ceiling and 1.5 km visibility to the ceiling and visibility minima of the VHF runway aligned instrument approach procedure to an alternative runway.
(c) when required by paragraph 8.1.10.3, add 300 ft ceiling and 1.5 km visibility to the ceiling and visibility minima of any other straight-in instrument approach procedure which utilises an aid other than those used in paragraphs 8.1.10.5(a) and 8.1.10.5(b) above.
8.1.10.6 The alternative minimum is the highest of those obtained above. Ceiling values should be rounded out to the nearest 50 ft. Visibility values should be rounded up to the next higher kilometre or half kilometre.
8.1.10.7 An extra margin over and above those mentioned above may be added if believed to be necessary because of peculiarities in the local weather patterns and/or difficulties in forecasting.
8.1.10.8 Invalidation of Special Alternate Minima. Instructions shall be promulgated in appropriate operational documents requiring aircraft operators/pilots-in-command to monitor the availability of required navigation aids and BoM meteorological services. These will include issuing of appropriate instructions requiring the reversion to standard alternate minima during periods when:
(a) local BoM METAR/SPECI are not available;
(b) BoM forecasting services are not available;
(c) protracted unserviceability (ie. greater than 7 days) of any ground equipment associated with the approach aid exists;
(d) an aerodrome control service is not provided.
8.1.11 International IFR Operations Outside Australia
8.1.11.1 Alternate minima must be determined:
(a) in accordance with paragraph 8.1.9; or
(b) by adding forecast tolerances for ceiling and visibility to the minima of the second lowest independent approach procedure suitable for the operation and for which the aircraft is equipped.
Note: If State forecast tolerances cannot be determined, or there is a doubt on the availability/reliability of the approach aid, a ceiling tolerance of 500 ft and visibility tolerance of 2 km must be used.
8.1.11.2 Except for ILS with approved Category I minima, the procedures used by each navigation system must be independent of each other. In determining alternate criteria, minima lower than ILS Category I must not be considered.
8.1.11.3 If the aerodrome has straight-in procedures to a runway that is not suitable for the operation and if circling is approved, the alternate minima must not be lower than the circling minima plus the forecast tolerances.
8.1.11.4 The approved alternate minima must be the greater of:
(a) the values determined by the foregoing paragraphs;
(b) the values approved by the State operating the aerodrome;
(c) 400 ft ceiling and 1,600 m visibility where the values determined in paragraph 8.1.11.4(a) above are based entirely on precision landing minima; or
(d) 800 ft ceiling and 3,000 m visibility where the values determined for paragraph 8.1.11.4(a) above are not based solely on precision landing minima.
Notes: 1. Independent means that the two procedures will not utilise a common radio navigation aid.
Note: 2. Where provided, a terminal area radar control service may be considered as an independent radio navigation aid for an approach to a point not later than 2 NM prior to the FAF.
8.1.11.5 The alternate minima determined above will vary with aerodrome, aircraft and radio aid serviceability and may be assessed only immediately prior to departure.
Notes: 1. Independent means that the two procedures will not utilise a common radio navigation aid.
Note: 2. Where provided, a terminal area radar control service may be considered as an independent radio navigation aid for the following parts of the procedure
Note: a. approach. To a point defined by CASA which shall not be later than the FAF
Note: b. missed approach. After a point defined by CASA which shall not be before the acceleration segment.
Note: 3. A categorised ILS may be considered as two independent procedures.
Note: 4. Operators may select nominal alternate values for ports. However, this does not absolve the captain of the pre-flight planning responsibility referred to in paragraph 8.1.11.5. Further, the operator must demonstrate that the value selected will satisfy paragraph 8.1.11 for all operations, both scheduled and unscheduled which may occur during the calendar period of application of the values selected. The demonstration must account for the three standard deviation wind values for both landing and crosswind components and may account for a downwind landing to the value allowed in the relevant aircraft certification.
8.1.12 Australian Differences to ICAO PANS-OPS Vol II
8.1.12.1 Circling Area. Where the circling area has been segmented to facilitate a lower minima and the missed approach point is located within the NO CIRCLING area, the area should be extended by an arc of no less than 2 NM to include the missed approach point within the applicable circling area. (See Figure 8‑3.)
Circling area modified to exclude MAPT
Figure 8‑3: Circling area modified to exclude MAPT
8.1.12.2 Height Above Aerodrome (HAA) and Height Above Threshold (HAT). The minima for non-precision approach procedures shall include a HAA, and for precision approach procedures shall include a HAT.
8.1.12.3 GPS Non-Precision Approach Missed Approach Procedures—Use of Secondary Areas. This instruction clarifies the application of secondary areas in the design of GPS NPA missed approach procedures within the Australian FIR.
(a) ICAO PANS-OPS Vol II Part III paragraph 33.7.2 and Appendix paragraph 6.5 support the use of secondary areas for GPS NPA missed approach design. However, the text following the asterisks in Figures III-33-6 and III-33-7 state that, until further operational experience is obtained with basic GNSS receivers, the full width of the missed approach area should be treated as the primary area.
(b) Until the ICAO position is reviewed, the following standards are to be applied to GPS NPA missed approach design within the Australian FIR. The provisions of PANS-OPS Vol II Part III paragraph 7.2.2 may be used for straight missed approach segments. Secondary areas will not apply to turning missed approach procedures after the earliest turn point on the inner edge of the turn and the intersection of the extended secondary splay and the wind spiral on the outer edge of the turn. Refer to PANS-OPS Vol II Part III paragraph 7.3.5.5 and Figure III-7-23 and III-7-27.
8.1.12.4 Location of missed approach point
8.1.12.4.1 For a runway-aligned approach, the missed approach point (MAPt) must be located at or before the threshold.
8.1.12.4.2 Where the final approach is not aligned with the runway centre line, the optimum location is the intersection of the final approach course and the extended runway centre line.
8.1.12.4.3 The MAPt may be moved closer to the FAF to provide obstacle clearance in the missed approach area provided that the MDA/H is not lower than the altitude/height on the design descent gradient at the MAPt.
8.1.13 Table of Operationally Equivalent Values
8.1.13.1 The following metres (m) to statute mile (mile (statute)) or feet (ft) value are deemed to be equivalent for operational purposes.
Table 8‑3: Operationally Equivalent Values
Visibility
RVR
400 m = ¼ mile (statute)
50 m = 150 ft
800 m = ½ mile (statute)
75 m = 250 ft
1,200 m = ¾ mile (statute)
100 m = 300 ft
1,600 m = 1 mile (statute)
150 m = 500 ft
2,000 m = 1 ¼ mile (statute)
175 m = 600 ft
2,400 m = 1 ½ mile (statute)
200 m = 700 ft
2,800 m = 1 ¾ mile (statute)
300 m = 1,000 ft
3,200 m = 2 mile (statute)
350 m = 1,200 ft
3,600 m = 2 ¼ mile (statute)
400 m = 1,400 ft
4,000 m = 2 ½ mile (statute)
500 m = 1,600 ft
4,400 m = 2 ¾ mile (statute)
550 m = 1,800 ft
4,800 m = 3 mile (statute)
600 m = 2,000 ft
800 m = 2,400 ft
1,000 m = 3,000 ft
1,200 m = 4,000 ft
1,600 m = 5,000 ft
2,000 m = 6,000 ft.
8.1.14 Special Authorisation Category I Approach Procedures
8.1.14.1 Scope. Paragraph 8.1.14 provides the requirements for designing and publishing an SA Category I approach procedure at a runway with reduced lighting with:
(a) a DH of 150 ft or higher; and
(b) a visibility minimum of 450 m or longer RVR.
8.1.14.2 Air Traffic Control. The aerodrome at which the runway is located must be a controlled aerodrome.
Note: Aircraft operators will not be permitted to conduct SA Category I instrument approach operations unless aerodrome control is in operation.
8.1.14.3 Runway Eligibility. An SA Category I approach procedure must not be designed for a runway unless:
(a) the runway has, or is qualified for, a precision approach Category I ILS procedure; and
(b) the aerodrome operator has given the designer information that the runway meets the requirements of the Manual of Standards (MOS) – Part 139 Aerodromes for SA Category I, SA Category II, Category II or Category III instrument approach operations.
Note: The specifications for a runway suitable for supporting SA Category I and SA Category II instrument approach operations can be found in Chapter 2 of the Manual of Standards (MOS) – Part 139 Aerodromes.
8.1.14.4 Precision Approach Facilities. The relevant aeronautical telecommunications service and radio navigation service provider must have given the designer information that the runway has precision approach facilities suitable for SA Category I operations, including information about whether the precision approach aid is suitable for only HUD-equipped aircraft.
8.1.14.5 Instrument Approach Procedure. The approach procedure must be designed in accordance with the standards PANS‑OPS Category I or II criteria, using the Height loss/altimeter margin for radio altimeters.
8.1.14.6 The SA Category I DH minimum must be the higher of the following:
(a) 150 ft;
(b) the calculated OCH.
8.1.14.7 The RA and DA minima must be calculated directly from the calculated DH value without rounding.
8.1.14.8 The SA Category I RVR minima must be derived in accordance with Table 8‑4, taking into account the type and length of the ALS and the DH.
8.1.14.9 Instrument Approach Chart. On the instrument approach chart for SA Category I approach procedures:
(a) the SA Category I minima must be associated with a chart note stating ‘Special aircrew and aircraft certification required’ or similar words to that effect; and
(b) for procedures that are limited to HUD-only operations — a method must be used to clearly indicate this limitation.
8.1.15 Special Authorisation Category II Approach Procedures
8.1.15.1 Scope. Paragragh 8.1.15 provides the requirements for designing and publishing an SA Category II approach procedure with:
(a) a DH of 100 ft or higher; and
(b) a visibility minimum of 350 m or longer RVR.
Note: As detailed below, for an SA Category II approach procedure, the landing system and some ground facilities must meet all Category II requirements. However, Category II and III approach lighting, TDZ lighting and runway centreline lighting is not necessarily required.
8.1.15.2 Air Traffic Control. The aerodrome at which the runway is located must be a controlled aerodrome.
Note: Aircraft operators will not be permitted to conduct SA Category II instrument approach operations unless aerodrome control is in operation.
8.1.15.3 Runway Eligibility. An SA Category II approach procedure must not be designed for a runway unless:
(a) the runway has, or is qualified for, a precision approach Category I ILS procedure; and
(b) the aerodrome operator has given the designer information that the runway meets the requirements of the Manual of Standards (MOS) – Part 139 Aerodromes for SA Category II, Category II or Category III instrument approach operations.
Note: The specifications for a runway suitable for supporting SA Category II instrument approach operations can be found in Chapter 2 of the Manual of Standards (MOS) – Part 139 Aerodromes.
8.1.15.4 Precision Approach Facilities. The relevant aeronautical telecommunications service and radio navigation service provider must have given the designer information that the runway has precision approach facilities suitable for SA Category II operations.
8.1.15.5 Instrument Approach Procedure. The SA Category II DH minimum must be the higher of the following:
(a) 100 ft;
(b) the calculated OCH.
8.1.15.6 The RA and DA minima must be calculated directly from the calculated DH value without rounding.
8.1.15.7 The SA Category II RVR minima must be the longest of the following:
(a) for a runway with TDZ lights and no runway centreline lights — 400 m;
(b) for a runway with no TDZ lights and no runway centreline lights — 450 m;
(c) the distance derived in accordance with Table 8‑5, taking into account the type and length of the ALS, the aircraft category and the DH.
8.1.15.8 Instrument Approach Chart. On the instrument approach chart for SA Category II approach procedures, the SA Category II minima must be associated with a chart note stating ‘Special aircrew and aircraft certification required’ or similar words to that effect.