Document ID: chunk:federal_register_of_legislation:F2022C00813:reg:300:p9
Version: federal_register_of_legislation:F2022C00813
Segment Type: reg
Provision Reference: reg 300 (pt 9/27)
Character Range: 93766–96767

that the LSALT determined shall be at least 1,000 ft above the highest obstacle located within the area concerned.

8.2.1.2              The purpose of this standard is to outline the rules and parameters to be used for the calculation of LSALT for IFR en-route operations. The particular issues addressed are:

(a)         effective areas;

(b)         charts;

(c)          altitude tolerances;

(d)         failure of radio navigation aids;

(e)         applicability.

8.2.2                   Effective Areas

8.2.2.1              Route defined by Radio Navigation Aids or by Dead Reckoning. The area to be considered for the LSALT calculation for a particular route or route segment must be a 5 NM area surrounding and including the route navigation tolerance area. The navigation tolerance must be based on an expanding track tolerance of ± 10.3° from the navigation aids which provide track guidance, and ±15° when no track guidance is available and DR navigation is required to be used. The maximum width of the route navigation tolerance area is 50 NM. For route or route segments served by VORs, the navigation aid coverage to be applied for the determination of the route navigation tolerance area must be the lesser of 60 NM or the maximum coverage published in ERSA. The effective areas for various circumstances are shown at paragraph 8.2.5.

8.2.2.2              Operations with Area Navigation Systems (including GPS). The area to be considered in specifying the LSALT applicable to any route or route segment must be as defined in paragraph 8.2.2.1 with an expanding track tolerance of ±10.3° to a maximum width of 30NM either side of track for conventional area navigation (RNAV) systems and 7 NM for GPS.

8.2.2.3              RNP operations. For routes flown by aircraft operating under a RNP approval, LSALT may be calculated in accordance with the standards contained in ICAO Doc 8168.

8.2.2.4              Navigation Charts. In specifying the LSALT for any latitude/longitude grid, only the area within the latitude/longitude grid need be considered.

8.2.3                   Charts

8.2.3.1              The chart recommended for plotting navigation tolerance areas and the extraction of terrain/obstacle information is the ICAO 1:1,000,000 WAC Series chart. However, whenever doubt exists concerning the accuracy of the information on the WAC, larger scale maps must be used. The RAAF Joint Operations Graphic (Air) Chart, at a scale of 1:250,000, is ideal for this purpose.

8.2.3.2              The terrain to be considered in the determination of the LSALT for any route segment must be:

(a)         when heights are shown on charts by spot heights and hachuring only—the highest spot height within the navigation tolerance area.

(b)         where heights are shown on charts as spot heights, contours and hypsometric tints—the highest spot height within the navigation tolerance area or, where there is no spot height, the highest terrain within the intruding contours.