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On the LEGS Page, a VNAVCompatible
Path Will Have:
• An RWxx or MXxx waypoint at or before the
approach end of the runway
– The waypoint altitude constraint will result in
approximately 50 feet threshold crossing height
(TCH)
– Examples (runway 12, TDZE at 1000’ MSL)
–RW12 170/1050
– MA12 170/1190
• A “GP” angle shown on the LEGS page for the final
approach segment
The Boeing Company W100.29
FMC Legs Page Shows
Glide Path Angle
The Boeing Company W100.30
Approach Diagram Shows G.P.
Angle and VNAV Compatibility
The Boeing Company W100.31
VNAV DA(H)s also show VNAV
compatibility
The Boeing Company W100.32
Types of Approaches That Are Not
VNAV-Compatible
• Approaches that do not have a GP angle, and
• There is no RWxx or MXxx waypoint with an
appropriate path terminating at approximately 50’
above the runway threshold, or
• The missed approach point is beyond the runway
threshold
The Boeing Company W100.33
FAA AC 120-29A Contains
Guidance on Use of VNAV
• VNAV approaches are considered as a “Category I Approach”
with a decision altitude (DA(H))
• VOR, VOR/DME, NDB, LOC or LOC BC approaches may be
flown with DA(H)s not less than 250 feet using VNAV, with
appropriate operational approval and equipment
• A DA (QNH barometric altitude) is used
• Use of a published VNAV path, or GP angle, is required when
a DA(H) is used
The Boeing Company W100.34
FAA HBAT 99-08 Permits Use of
MDA(H)s as DA(H)s
• Eligible procedures include: VOR, VOR/DME, NDB,
RNAV, GPS, LOC, LOC-BC, LDA and SDF
• When VNAV PTH is used, a slight momentary
descent below the published DA(H) during the
missed approach is acceptable
• RNP 0.3 capability or less is required
• Eligible procedures must have a visual segment
obstacle assessment
• Without a published DA(H), the MDA(H) may be
used as a DA(H) (with operational approval)
The Boeing Company W100.35
FAA Visual Segment Obstacle
Assessment Complete for:
• ILS approaches with a published GP angle
• Runways with a VASI or PAPI
• RNAV approaches with a published VNAV DA (H)
The Boeing Company W100.36
The GP Angle Provides Obstacle
Clearance
• A published GP angle is evidence that:
– the VNAV path will arrive at the published TCH, and
– complies with underlying step-down altitudes
• The GP angle is constructed “backward” from the 50’
runway waypoint and normally intersects the FAF altitude
constraint
50 ft.
RW12
FAF
3.00
The Boeing Company W100.37
The GP Angle Complies with the
Step-down Altitudes
The Boeing Company W100.38
Most GP Angles Have a “Fly-off”
• If the distance from the FAF to the runway is greater
than required for an immediate descent
• The “fly-off” may be indicated on the chart. Some
FMCs (737 only) provide a “T/D” on the map display
at the end of the “fly-off.”
• The FMC will command level flight in VNAV PTH
until reaching the descent path
The Boeing Company W100.39
GP “Flyoff” Example
The Boeing Company W100.40
Non-ILS VNAV Path Availability:
Total vs.% Flyable in VNAV
• Europe 1028/93%
• Africa 330/87%
• S. America 337/56%
• Middle East 468/87%
• USA 4400/90%
• Canada 657/90%
• Asia/Pacific 639/90%
•Based on an informal navigation data base survey
•Jeppesen is in the process of recoding all non-ILS
approaches
The Boeing Company W100.41
Typical VNAV Approach
Procedure (except 737-3/4/500)
Prior to approach
• Select approach procedure
• Verify/enter RNP
Final descent and at least 300’ below MAP Altitude
• Set missed approach altitude
At DA (or MDA + 50 feet)
• Disengage Autopilot/Autothrottle
or
• Go-Around
Approx 2 NM prior to FAF
• Set MDA/DA
• Verify/select roll mode (LNAV, or other)
• Select VNAV (VNAV PTH) & speed intervention
• Autopilot engaged
((RRWWXXXX oorr MMXXXXXX))
((FFAAFF))
The Boeing Company W100.42
Typical VNAV Approach
Procedure (737-3/4/500, U7.1 or later)
Prior to approach
• Select approach procedure
• Verify/enter RNP
Approaching MDA/DA
• Set missed approach altitude
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RNAV/RNP Operations & VNAV Approaches(3)
