You will find details from time to time on the data plates on a lot of access equipment with figures relating to angles you can drive on at height when outriggers are fitted to the machine. Worksafe Victoria stipulates that wherever outriggers are fitted they must be used before elevation, that is not just limited to muddy or sloping ground, even if you are on a flat concrete surface if you have outriggers on the machine you must deploy them before going up to height.