Blackcoffeenosugar,
Approach climb gradient(for twins) is
2.1%.assuming
S.E.;G/A FLAPS;L/Gup;live Eng at max avail thrust.
For
cat II and above the requirement is
2.5% from
Airfield elevation.
Before commencing an approach if it is determined that 2.5% can be met then there is no problem flying the published G/A even if initiated below cat I minima since all charts are based on 2.5%(those that require higher, are stated on the chart.)
hope that answers your concern about a G/A below minima.
In situations where you cannot meet 2.5% or the specific gradient required at some airfields, the crew can, with prior advice to ATC (preferably before commencing the approach) choose to fly the E.O.sid for want of a better option.
hope that helps
cheers
