Aircraft Operations. Volume II - Construction of Visual and Instrument ...

I-4-3-App A-4 Procedures — Aircraft Operations — Volume II
b) start point of the turn defined by VOR/DME indication: 7 km (4 NM).
These values are adequate provided that the length of the first leg does not exceed 19 km (10 NM); otherwise, they
should be increased by 15 per cent of the distance in excess of 19 km (10 NM). Example: Start point of the turn
defined by VOR intersection; for a 37 km (20 NM) first leg, the length of the DR segment shall not be less than
10.5 km or 6.5 NM.
23/11/06
3.3 Characteristics of the U-type procedures
3.3.1 Position of the initial approach fix (IAF). The IAF can be a facility (VOR or VOR/DME) or a fix from
which track guidance is available. This fix or facility shall be located outside a sector contained between the final
approach path and a straight line L (see Figure I-4-3-App A-1). Line L is determined as follows:
a) from the FAP draw line D at an angle to the final approach path.
The length of D varies with the type of facility. Lengths for each type appear in Table I-4-3-App A-3; and
b) at the end point of line D, draw line L perpendicular to line D.
3.3.1.1 Values for were determined as follows:
a) take the angle (45°) between the dead reckoning segment and the ILS axis;
b) add the maximum angle between the first leg of the initial segment and the dead reckoning segment:
1) 45° + 120° = 165° for VOR/DME; and
2) 45° + 105° = 150° for VOR/VOR;
c) take the total from steps 1 and 2, and subtract this from 180. This gives the maximum angle between the first
leg of the initial segment and the reverse of ILS axis:
1) 180° – 165° = 15° for VOR/DME; and
2) 180° – 150° = 30° for VOR/VOR;
d) subtract the value obtained in c) from 90° in order to have the direction of the perpendicular:
1) 90° – 15° = 75° for VOR/DME; and
2) 90° – 30° = 60° for VOR/VOR; and
e) subtract a buffer value of 5° for technical tolerance to give the following values:
1) 70° for VOR/DME; and
2) 55° for VOR/VOR.