Aircraft Operations

Chapter 1
APV/BARO-VNAV APPROACH PROCEDURES
Note.— Barometric vertical navigation (baro-VNAV) is a navigation system that presents to the pilot computed
vertical guidance referenced to a specified vertical path angle (VPA), nominally 3°. The computer-resolved vertical
guidance is based on barometric altitude and is specified as a VPA from reference datum height (RDH).
1.1 GENERAL
1.1.1 Procedure classification
1.1.1.1 APV/baro-VNAV approach procedures are classified as instrument approach procedures in support of
approach and landing operations with vertical guidance (see Annex 6). Such procedures are promulgated with a
decision altitude/height (DA/H). They should not be confused with classical non-precision approach (NPA) procedures,
which specify a minimum descent altitude/height (MDA/H) below which the aircraft must not descend.
1.1.1.2 APV/baro-VNAV procedures provide a greater margin of safety than non-precision approach procedures
by providing for a guided, stabilized descent to landing. They are particularly relevant to large commercial jet transport
aircraft, for which they are considered safer than the alternative technique of an early descent to minimum altitudes.
1.1.1.3 However, the inaccuracies inherent in barometric altimeters, combined with the certificated performance
of the specific area navigation (RNAV) mode used, make these procedures less accurate than precision approach
systems. In particular, with certain systems the aircraft may not arrive within the Annex 14 obstacle-free surfaces, and
the pilot should consider this possibility when making the decision to land at DA/H.
1.1.1.4 The lateral portion of APV/baro-VNAV criteria are based on RNAV non-precision criteria. However, the
FAF is not part of the APV/baro-VNAV procedure and is replaced by a final approach point, although the RNAV FAF
may be used as a final approach course fix in database design. Similarly, the MAPt is replaced by an aircraft-categorydependent
DA/H.
1.1.1.5 The APV/baro-VNAV minimum DH is 75 m (246 ft) plus a height loss margin. However, this minimum
DH limit must be increased by the operator to at least 90 m (295 ft) plus a height loss margin when the lateral
navigation system is not certificated to ensure the aircraft will arrive within the Annex 14 inner approach, inner
transitional and balked landing surfaces (extended as necessary above the inner horizontal surface to OCH) with a high
degree of probability.
1.2 SYSTEM PERFORMANCE
1.2.1 The factors upon which the vertical navigational performance of the baro-VNAV procedure depends are
outlined below.
II-4-1-1 23/11/06