So long as you do not do extensive cut and filling of the land, and it forms part of, or is incidental to your existing "Approved use" of the land it would not be an issue. But if you change the use of the land, such as operating a commercial operation you would require development approval. This is a generalisation, and some Councils may try the bluff act on. If you build a shed to house the aeroplane, you would require "Development Approval" for the shed, but if the use was spasmodic and doesn't upset the neighbours too much, should not be too much of an issue.
It would be worth having a look at the "Development Plan" for the Council in the area that you intend to move into, to check if an airfield is listed as "Non-Complying" use of the land.
