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

Chapter 2
TERMINAL AREA FIXES
2.1 GENERAL
2.1.1 Because all navigation facilities and waypoints have accuracy limitations, the geographic point which is
identified is not precise, but may be anywhere within an area which surrounds the nominal point. The nominal point
can be defined by:
a) an intersection (see 2.3, “Fix tolerance and fix tolerance area for intersecting fixes”);
b) overheading a facility (see 2.5, “Fix tolerance overheading a VOR or NDB”);
c) an RNAV waypoint; and
d) other kinds of navigation aids (see 2.4, “Fix tolerance for other types of navigation instruments”).
2.1.2 As an example, Figure I-2-2-1 illustrates the intersection of an arc and a radial from the same VOR/DME
facility, as well as the intersection of two radials or bearings from different navigation facilities. The area of
intersection formed in this way is referred to in this document as the “fix tolerance area”.
2.2 TERMINAL AREA FIXES
2.2.1 Terminal area fixes include, but are not limited to:
a) the initial approach fix (IAF);
b) the intermediate approach fix (IF);
c) the final approach fix (FAF); and
d) the holding fix,
and when necessary, a fix to mark the missed approach point (MAPt), or the turning point (TP).
2.2.2 Terminal area fixes should be based on similar navigation systems. The use of mixed type (as VHF/LF)
fixes should be limited to those intersections where no satisfactory alternative exists.
2.3 FIX TOLERANCE AND FIX TOLERANCE AREA FOR INTERSECTING FIXES
The fix tolerance and fix tolerance area are obtained by using navigation information from either collocated or noncollocated
facilities as shown in Figure I-2-2-1.
I-2-2-1 23/11/06