Not just Sydney: Melbourne's crane problem, documented in 2014

More than a decade ago, aviation consultant Ian Thompson set out how airspace rules around Essendon Airport shape what can be built in the Melbourne CBD. His explanation of the system still holds: a state planning permit doesn't allow a building to enter an airport's prescribed airspace, and separate federal approval is required.

The piece is clearest on the difference between the two surfaces. Buildings can penetrate the Obstacle Limitation Surface if there's no significant risk to aviation safety, but no permanent obstruction is allowed in a PANS-OPS surface, including lift overruns and aerials. Cranes can penetrate temporarily, for up to three months and only with the airport operator's agreement. Thompson argued that isn't long enough for towers sitting just below the surface, which means buildings probably end up lower than they otherwise could be.

He also made a case HAAPA shares: risk depends on context. With moderate traffic, few aircraft flying the relevant missed approach, and the CBD at least 9km from the airport, he argued flight procedures could be adjusted to allow a higher surface or longer crane access without compromising safety.

Some details have changed since 2014, but the core issue has not: the approvals path for building heights and temporary crane access remains slow and hard to predict. That's one of the reforms HAAPA is pushing for.

Download: Aviation Impact on Building Development in the Melbourne CBD (PDF, republished with permission)
Read more: Aviation Impact on Building Development in the Melbourne CBD, Urban (2014)

Related: PANS-OPS: the invisible ceiling over Sydney's skyline