Minimum Descent Altitude (MDA (H))/ Decision Altitude (DA(H))
When reaching the DA(H) or MDA(H), be prepared to continue the approach to landing or execute an immediate go-around. If continuing to landing, disengage the autopilot and disconnect the autothrottle no later than the single autopilot minimum use height.
Note: If using an MDA(H), initiating a missed approach approximately 50 feet above MDA(H) may be necessary to avoid descending below the MDA(H) during the missed approach, if required for the procedure or by the regulatory authority.
The pilot not flying should expand the instrument scan to include outside visual cues when approaching DA(H) or MDA(H). Do not continue the approach below DA(H) or 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 DA(H) or 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. While VNAV PTH guidance may still be used as a reference once the airplane is below DA(H) or MDA(H), the primary means of approach guidance is visual.
Note: VNAV path guidance transitions to level flight once the missed approach fix is passed.
Vertical Speed Approach
Use the MDA(H) specified for the instrument procedure.
The pilot not flying 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.
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.
VDPs are indicated on some non-ILS approach charts by a "V" symbol. The distance to the runway is shown below the “V” symbol. If no VDP is given, the crew can determine the point where to begin the visual descent by determining the height above the airport (HAA) of the MDA(H) and use 300 feet per NM distance to the runway.
In the following example, an MDA(H) of 550 feet MSL with a 100 feet touchdown zone elevation results in a HAA of 450 feet. At 300 feet per NM, the point to begin the visual descent is 1 . NM distance from the runway.
Most VDPs are between 1 and 2 NM from the runway. The following table provides more examples.
HAA (feet) 300 400 450 500 600 700
VDP Distance, NM 1.0 1.3 1.5 1.7 2.0 2.3
Note: If flying a VNAV path approach and the airplane remains on the published path, then the VDP is automatically complied with when the airplane arrives at the DA(H) or MDA(H). It is not necessary to determine the point to begin the visual descent for VNAV path approaches for this reason.
When flying an instrument approach using V/S, if the pilot adjusts the altitude range arc to approximately the VDP distance in front of the runway by varying the vertical speed, the airplane will remain close to or on the proper path for typical non-ILS approaches.
Missed Approach - Non-ILS
Refer to Missed Approach/Go-Around - All Approaches, this chapter.
Circling Approach - General
The circling approach should be flown with landing gear down, flaps 20, and at flaps 20 maneuvering speed. Use the weather minima associated with the anticipated circling speed. As an option the approach may be flown with flaps 25 or 30. Maintain MDA(H) using ALT HOLD mode and use HDG SEL or HDG HOLD for the maneuvering portion of the circling approach. If circling from an ILS approach, fly the ILS in LOC and VNAV or V/S modes.
Note: If the MDA(H) does not end in “00”, select ALT HOLD when the airplane reaches MDA(H).
Use of the APP mode for descent to a circling approach is not recommended for several reasons:
.
the AFDS does not level off at MCP altitude
