john_smith
Do you understand why we are no longer required to add 50' to the MDA to create an artificial DA?
Enlighten me, please. I can understand, that the adding of 50 feet is not required in the sense of a hard figure for all aircraft and all configurations, thus using the judgement of the crew how much feet they need to add in their situation or what kind of procedure they may use for go around to make sure they stay at or above MDA. If you are saying, that the MDA doesn´t need to be treated as hard altitude anymore, then please explain with reference to the definition below.
Definition
The Minimum Descent Altitude (MDA) or Minimum Descent Height (MDH) is a specified altitude or height in a Non-Precision Approach or Circling Approach below which descent must not be made without the required visual reference. (ICAO Anex 6)
Note 1. MDA is referenced to mean sea level and MDH is referenced to the aerodrome elevation or to the threshold elevation if that is more than 2 m (7 ft) below the aerodrome elevation. An MDH for a circling approach is referenced to the aerodrome elevation.
Note 2. The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path. In the case of a circling approach the required visual reference is the runway environment.
Note 3. For convenience when both expressions are used they may be written in the form “minimum descent altitude/height” and abbreviated “MDA/H”.
http://www.skybrary.aero/images/thum...x-101020-1.jpg
An MDA/H differs from a DA/H in that the aircraft must be flown in such a way that it does not descend below the MDA/H unless the required visual reference has been established. Typically, an aircraft will continue at the MDA/H until a pre-calculated missed approach point is reached; if the required visual reference is not established by that point a Missed Approach will be flown.
How do you make sure, that flying a CDA you are not descending through the MDA / MDH on the go around, if the visual references are not established when reaching MDA / MDH?
Some reference here:
NON-PRECISION INSTRUMENT APPROACH USING CONTINUOUS
DESCENT FINAL APPROACH (CDFA) TECHNIQUES
Decision Approaching MDA.
Flying the publishedVDA will have the aircraft intersect the plane established by the MDA at a point before the MAP. Approaching the MDA, the pilot has two choices:
continue the descent to land with required visualreferences, or
execute a missed approach, not allowing the aircraft to descend below the MDA. (See Annex, Figure 1B- ApproachExampleUsing ContinuousDescent Final Approach).