737 Flight Crew Training Manual
Several techniques may be used to achieve a constant angle path that arrives at MDA(H) at or near the VDP:
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the most accurate technique is to monitor the VNAV path deviation
indication on the map display and adjust descent rate to maintain the
airplane on the appropriate path. This technique requires the path to be
defined appropriately on the LEGS page and that the header GPx.xx is
displayed for the missed approach point or there is a RWxx, MXxx, or
named waypoint on the legs page with an altitude constraint which
corresponds to approximately 50 ft. threshold crossing height. When this
method is used, crews must ensure compliance with each minimum
altitude constraint on the final approach segment (step down fixes)
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select a descent rate that places the altitude range arc at or near the
stepdown fix or visual descent point (VDP). This technique requires the
stepdown fix or MDA(H) to be set in the MCP and may be difficult to use
in turbulent conditions. See the Visual Descent Point section for more
details on determining the VDP
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using 300 feet per mile for a 3° path, determine the desired HAA which
corresponds to the distance in NM from the runway end. The PM can then
call out recommended altitudes as the distance to the runway changes
(Example: 900 feet - 3 NM, 600 feet - 2NM, etc.). The descent rate should
be adjusted in small increments for significant deviations from the
nominal path.
Be prepared to land or go-around from the MDA(H) at the VDP. Note that a normal landing cannot be completed from the published missed approach point on many instrument approaches.
Approximately 300 feet above the MDA(H), select the missed approach altitude. Leaving the MDA(H), disengage the autopilot and disconnect the autothrottle. Turn both F/Ds OFF, then place both F/Ds ON. This eliminates unwanted commands for both pilots and allows F/D guidance in the event of a go-around. Complete the landing.
Minimum Descent Altitude/Height (MDA(H))
The pilot monitoring should expand the instrument scan to include outside visual cues when approaching MDA(H). Do not continue the approach below MDA(H) unless the airplane is in a position from which a normal approach to the runway of intended landing can be made and suitable visual reference can be maintained. Upon arrival at MDA(H) or any time thereafter, if any of the above requirements are not met, immediately execute the missed approach procedure.
When suitable visual reference is established, maintain the descent path to the flare. Do not descend below the visual glide path.
Copyright . The Boeing Company. See title page for details.
October 31, 2006 FCT 737 (TM) 5.59
Visual Descent Point
For a non-ILS approach, the VDP is defined as the position on final approach from which a normal descent from the MDA(H) to the runway touchdown point may be initiated when suitable visual reference is established. If the airplane arrives at the VDP, a stabilized visual segment is much easier to achieve since little or no flight path adjustment is required to continue to a normal touchdown.
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