CAO 20.7.4 is very specific that short dry grass must be used to determine takeoff distance
djpil, to quote
6.2 For aeroplanes operated on land, take-off distances are to be determined for a level short dry grass surface.
and
6.3 Where there is an approved foreign flight manual or a manufacturer’s data manual for an aeroplane that sets out the take-off distance required for that aeroplane, then that aeroplane must be operated so as to comply with either the requirements set out in paragraphs 6.1 and 6.2 or the requirements relating to take-off distance set out in either of those manuals.
There are no charts covering take off on short, dry grass so I'm obliged to comply with the highlighted portion of para 6.2. ie I can only operate from a paved, level, dry runway, since that is the only condition for which data is available.
Operate off anything else and run into the trees at the end the Feds are going to ask "how did you substantiate the take off performance? Please tender to the court the CASA approved chart".
So how does Farmer Fred go about operating his 182 to land and check his dams, bore pumps, troughs etc that CASA will accept as "legal", whatever that means? Paved, level, dry runways?