If descending in VNAV SPD, the AFDS changes to VNAV PTH automatically when approaching the FAF if the airplane is on or below the path. Reset the MCP to the DA(H)/MDA(H) approximately 2 NM before the FAF. If the AFDS enters ALT HOLD mode beyond the FAF, set DA(H)/MDA(H) in the MCP and select VNAV without delay. If VNAV ALT (as installed) has engaged beyond the FAF, set DA(H)/MDA(H) in the MCP and select altitude intervention without delay to enable continued descent on the final approach path. Execute a missed approach if the deviation above path becomes excessive enough to prevent achieving a stabilized approach.
Prior to final approach, the MCP altitude should be set at the appropriate altitude constraint (normally that for the next waypoint) to assure compliance with approach minimum altitudes while descending on the approach. To avoid leveling off, reset the MCP to the following waypoint altitude constraint as soon as the next waypoint altitude constraint is assured. However, if compliance with an altitude constraint is in question, consider leveling off or reducing the rate of descent to ensure a safe path.
Final Approach using VNAV
Approaching intercept heading, select flaps 5 and select LNAV or other appropriate roll mode. Approaching the FAF (approximately 2 NM), select gear down and flaps 15. Adjust speed if using speed intervention. Set the DA(H) or MDA(H) in the MCP altitude window, select VNAV, and ensure VNAV PTH and appropriate roll mode is annunciated.
Note: If desired altitude is not at an even 100 foot increment, set the MCP altitude to the nearest 100 ft. increment above the altitude constraint or MDA(H).
Note: For approach procedures where the vertical angle (“GP” angle shown on
the LEGS page) begins earlier in the approach (prior to the FAF), the MCP
may be set to the DA(H) or MDA(H) once established on the vertical
angle.
When initiating descent on the final approach path, select landing flaps, slow to final approach speed and do the Landing checklist. If the charted FAF is too close to the runway to permit a stabilized approach, consider establishing final approach pitch mode and configuring for approach and landing earlier than specified in the FCOM procedure.
Copyright . The Boeing Company. See title page for details.
5.48 FCT 737 (TM) October 31, 2006
737-300 - 737-500 With the MCP altitude set to DA(H) or MDA(H) and the airplane stabilized on the final approach path, the map altitude range arc assists in determining the visual descent point (VDP). When the airplane is approximately 300 feet above the MDA(H) and stabilized on final approach in VNAV PTH, set the MCP altitude to the missed approach altitude. When the MCP is set to an altitude above the current airplane altitude, the AFDS reverts to CWS P. VNAV path deviation indications on the map display assist in monitoring the vertical profile. The autopilot tracks the path in VNAV PTH, however the pilot must track the path in CWS P to arrive at, or near, the visual descent point by the DA(H) or MDA(H).
737-300 - 737-500 Setting the missed approach altitude at approximately 300' above the DA(H) or MDA(H) during an instrument approach using VNAV is done differently than on later 737 models for these reasons:
.
during an approach in strong gusty wind conditions, the AFDS may revert
from VNAV PTH to LVL CHG due to minimum speed reversion
protection. If the MCP altitude is set at or above the DA(H) or MDA(H),
the airplane will level off when reaching DA(H) or MDA(H) if there is no
pilot intervention, prevent descent into the terrain
.
setting the MCP should be delayed until approaching the DA(H) or
MDA(H) but before ALT ACQ since the AFDS will revert to CWS P
once the MCP is set to an altitude above the current airplane altitude.
737-600 - 737-900 With the MCP altitude set to DA(H) or MDA(H) and the airplane stabilized on the final approach path, the map altitude range arc assists in determining the visual descent point (VDP). As soon as the airplane is at least 300 feet below the missed approach altitude and stabilized on final approach in VNAV PTH, set the MCP altitude to the missed approach altitude. VNAV path deviation indications on the map display assist in monitoring the vertical profile. The autopilot tracks the path in VNAV PTH resulting in arrival at, or near, the visual descent point by the DA(H) or MDA(H).
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