In general, a large aircraft is fixed wing aircraft with maximum take-off weight of more than 5700kg, or helicopter with more than one engine (Reference: CASR1998 Vol 5, Page 236).

Similarly, a small aircraft is fixed wing aircraft with maximum take-off weight of not more than 5700kg, or helicopter with only one engine (Reference: CASR1998 Vol 5, Page 236).

The above holds true, except where specifically indicated otherwise by the Part 42 Manual of Standards. In certain exceptional cases, an aircraft can be defined as large or small irrespective of its maximum take-off weight or number of engines.

Currently, there is only one aircraft type which is an exceptional case under the Part 42 MOS. The Air Tractor (models 400, 500 and 800) are all classified as small (Reference: Part 42 MOS, Page 27).