123 Flinders Street and the Airport discussion

[Nort]

Why? Most aircraft, whenever I have flown out of Adelaide, take off over the gulf. If an aircraft is taking off towards the northeast, and encounters engine trouble, I assume it has to get out of the way of any incoming aircraft, but why not veer north, rather than towards the city? I'm not doubting what Paul is saying, I'm curious.

The direction of incoming and outgoing flights depends on the prevailing wind conditions. Some days they take off toward the hills and come in via the gulf, most days the opposite.

I used to work in the Telstra building, and some days they did fly very close.

Over North Adelaide correct?

I still don't see how that should affect the southern half of the CBD.
This proposed building and revised height/floors, will not be in the path of planes.
You have north adelaide/flight path, existing tallest buildings, then this proposal.

I once posted an example from America, which had taller buildings, with a flight path from a much busier airport, running practically parallel to their skyline.
The southern half of the CBD is where development should be focused, with or without flight path issues elsewhere.

I've held this view for a while, and I still hold it. The airport & parafield need to be relocated to the salt pans. It is surrounded mostly by industrial sites, and mangroves/torrens island. Aircraft noise will be minimal to residential.
But it's never going to happen because of shortsightedness.

You can argue that Adelaide airport should be moved (although I would disagree) but moving Adelaide Airport and Parafield to the salt pans doesn't make any sense.

Edinburgh is just next door to the salt pans/Parafield, which gives lots of restrictions on flight paths. Not to mention that if you are moving Adelaide Airport there you may as well eliminate Parafield Airport entirely since it would lose the things that make it a good training airfield.

edit: The unfortunate truth for Adelaide is that we don't need the airspace above the CBD for building yet. We have a large sprawling city and suburbs with low density. While most of us on here would like to see large developments there isn't much pressure for them even without height restrictions.

[Maximus]

Okay, so I’ve attempted to get some certainty about this issue by doing some more reading and asking questions of a few people who know more about this than any of us. What I’m posting here is nothing beyond what is publicly available, but it has been clarified and put into context by those individuals.

There are two types of ‘protected airspace’ around an airport: the OLS (Obstacle Limitation Surface) and PANS-OPS (Procedures for Air Navigation Services—Aircraft Operations) surface.

The OLS is shaped kind of like an upside-down hat. There is a lower, flat surface immediately around the airport runway, which then slopes upwards to an outer, upper, flat surface. The OLS is more or less the same size and shape for all airports, with the outer, upper, flat surface being 150m high and extending to 15km away from the airport. The Adelaide CBD is within the upward-sloping part of the OLS, hence the height contours on the map in the document that Shuz posted at the start of this thread.

Crucially, the OLS is the surface for which you need approval to breach if the height of your proposed structure will penetrate it. It’s not a restriction on building heights per se. It’s simply the level above which obstacles are considered a potential hazard to aircraft operations (particularly in the case of engine failure, poor visibility, etc) and must therefore be reported to CASA and approval received from the Federal Department of Infrastructure and Transport.

The PANS-OPS surface, however, is a restriction on building heights, as no structure is allowed to penetrate this surface. It is always higher than the OLS and the airspace above this surface must be retained for unimpeded aircraft operations.

Approval to penetrate the OLS is generally only denied if there’s a particular reason to do so; in practice, it’s almost always approved, so long as the PANS-OPS surface is not breached and subject to appropriate red, flashing lights being installed on the top of the structure. As noted earlier, seeking approval doesn’t cost anything, but the procedure must receive input from CASA, Airservices and the relevant airport.

Hope this helps. If we need more clarification, I might be able to find out more.

[Wayno]

thanks Maximus, your info aligns with our investigations circa 2007 and what we documented over here. If interested read through the 10 or so pages in that thread, and the submission doc. Several of us in this forum studied OLS & PANS-OPS. Personally I spoke with the General Manager at AAL (who loves talking about this sort of stuff) and a 'friend of a friend' at CASA who provided lots of useful info over a few beers at the Edinburgh Hotel

[Maximus]

Yeah, sorry if I covered old ground there (I was around on here when that submission was developed, but didn't know anywhere near as much about aviation then as I do know), but it's worth revisiting, because some of the discussion in this thread kinda misses the point -- which is that, in practice, the only thing from an aviation perspective likely to stop the approval of a tall building in the Adelaide CBD is if it would penetrate the PANS-OPS surface. Yes, the OLS is relevant, but it's highly unlikely to be a limiter.