If you are dropping food parcels to a yacht that has run aground on a small island, what height can you legally drop the parcels from? Is it lower than 500'? And where is the reference? CAR 157 says you can go below 1000 but what about 500'?

Also what does 29.5 mean when it says

[i]7.1 Unless a flight at a lower height is essential to the efficient conduct of a dropping operation and such an operation is occasioned by an emergency:
(a) an aeroplane shall not fly over any populous area at a height lower than 1500 feet above the terrain; and
(b) an aircraft other than an aeroplane shall not fly over any populous area at a height lower than 1000 above the terrain.[/i]

What is an aircraft other than an aeroplane?
Why are these heights more than the minimum heights specified in CAR 157?

Sorry to ask lots of questions at once

-Cath