Determination of DA(H)

[shazapis]

BOAC,

Hm, I don't think this is very conclusive. First of all, the link points to a "chart clinic" article that is quite old (1999-ish). A lot have changed since.
Then, I believe that it doesn't really apply outside FAA-landia. For instance (extract from this document):

"And the big “IF.” The MDA may be used as a
DA only if there has been a visual segment
obstacle assessment made for the straight-in
landing runway. The FAA has stated that
there has been an obstacle assessment when
the runway has a VASI or PAPI as a visual
guidance system indicator, an electronic
glideslope, or an RNAV approach published
with a decision altitude.
Since an obstacle assessment has been made,
the FAA has authorized the DA since it is
assumed that a momentary descent will be
made below the DA during the execution of
a missed approach.
When there is a VDP, it should be at the point
where the descent angle meets the MDA."

So, no addition to the MDA(H) if the runway has PAPI lights? Also, the point about "momentary descent etc" is clearly in violation of PANS-OPS.

I found a reference to the 50 ft, but not on a regulatory document - it's in an FSF ALAR briefing note (7.2, page 5) that states

"Approaching the MDA(H)
At an altitude corresponding to the MDA(H) plus 1/10 the rate of descent (typically MDA[H] plus 50 to 100 feet), anticipate a go-around decision to avoid descent below the MDA[H], as required by applicable regulations".

I still believe that the safest option on CDFA NPAs is to add 50 feet to all procedures, until there is a positive way to identify DA(H) procedures that originate from the authority and not the charting company...

Spiros Chazapis
Athens, Greece