Few years back I was very involved with the CDA topic.
At that time the 50 feet increment was just an arbitrary number that some operators used but in fact the requirement was just to establish an SOP with an increase to MDA to make sure this was not busted during the G/A.
Of course this depends on the altitude loss for each particular aircraft type.
The 50 feet number may be a good one size fits "all" but maybe not required as standard by most regulators.
No increase to minimums was only allowed *if* a DA was published *and* the operator had received authorization for such operations.
Something to keep in mind if you are using Baro VNAV is that most of the FMS's can not be compensated for temperature.
(An ILS GS is not affected by this.)
Operators have been using CDA for more than 25 years with excellent results.(Adding cushion to MDA) Published DA's for NPA's and authorizations for their use is not very old
As an active line pilot/Check Airman with some 32K hours and still a few years to go I celebrate the excellent posts provided here promoting the use of CDA.
Brgds.
Manuel
Last edited by manuel ortiz; 11th Jan 2010 at 01:34.