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Yesterday, I saw an AOPA post on Facebook informing the public that KUAO will now have a control tower. Nothing special about that until I noticed that they were designating quadrants to the south and west as Class D 1200 MSL - 2700 MSL, according to AOPA. I haven't been able to find that actual designation on the chart or the inset itself, but I do see how they have a shelf outlined there. The other strange thing is that, while there is a Class D ring around the field, the magenta would indicate that the field is still untowered. Could that be a typo? Possibly a transitional phase? Never seen something quite like this before.

Kind of strange, but my inner-nerd would like to see what others have to say.

The field came to life as of today, here are the relevant NOTAMs for the field:

!UAO 10/018 UAO SVC CLEARANCE DELIVERY 119.15 CHANGED TO PORTLAND APP
CLEARANCE DELIVERY 119.95 DLY 0400-1400 1510160400-PERM
!UAO 10/017 UAO COM COMMON TFC ADVISORY FREQ 120.35 COMMISSIONED DLY
0400-1400 1510160400-PERM
!UAO 10/016 UAO SVC PCL TWY LGT, EDGE LGT, VASI, ALS COMMISSIONED KEY
FREQ 120.35 7 TIMES HIGH/5 TIMES MEDIUM/3 TIMES LOW INTST DLY
0400-1400 1510160400-PERM
!UAO 10/010 UAO COM LOCAL CTL 120.35, GND CTL/CLEARANCE DELIVERY
119.15 COMMISSIONED DLY 1400-0400 1510151400-PERM
!UAO 10/009 UAO SVC PCL RWY 35 VASI FREQ CHANGED TO 120.35 1510151400-PERM
!UAO 10/008 UAO SVC PCL RWY 17 VASI FREQ CHANGED TO 120.35 1510151400-PERM
!UAO 10/007 UAO SVC PCL RWY 17 ALS FREQ CHANGED TO 120.35 1510151400-PERM
!UAO 10/005 UAO SVC TWR COMMISSIONED 1510151400-PERM

The Delta airspace was created for a tower that wasn't yet open, that's what the chart is showing. By the next sectional chart update, it'll be shown as a regular Class D, I suspect. For now, it's the NOTAMs that are bringing it to life. Tower freq is 120.35. Heaven help someone who flies there without checking the NOTAMs! Thankfully, apps like ForeFlight pretty much jam the NOTAMs down your throat (which is a good thing), so it'll be hard to miss.

asad112 wrote:Nothing special about that until I noticed that they were designating quadrants to the south and west as Class D 1200 MSL - 2700 MSL, according to AOPA. I haven't been able to find that actual designation on the chart or the inset itself, but I do see how they have a shelf outlined there.

There have been a few instances of things like this happening across the U.S. in the last two or three years. Some of the airports receiving towers are in close proximity to other non-towered airports. Instead of requiring the pilots at the neighboring airports to communicate with the tower, they exclude the neighboring airports from the Class D altogether. It's a nice option, but unfortunately the pilots at the neighboring airports that underlie the new Class D airspace are bound to at least 3SM visibility rather than the usual 1SM permitted by Class G minima.

Peter brought up a good point when I was chatting with him about this. Here's the NPRM:

That airspace extending upward from the surface to and including
2,700 feet within a 5-mile radius of Aurora State Airport, excluding
that airspace below 1,300 feet beyond 3.3 miles from the airport
from the 142[deg] bearing clockwise to the 172[deg] bearing from the
airport, and the 250[deg] bearing clockwise to the 266[deg] bearing
from the airport, and that airspace within a 0.5-mile radius of
Workman Airpark, OR. This Class D airspace area is effective during
the specific dates and times established in advance by a Notice to
Airmen. The effective date and time will thereafter be continuously
published in the Airport/Facility Directory.

This is going to cause confusion for non-local pilots from now until eternity unless they can get it listed somewhere prominently on the chart.

So there are 2 points here both of which are interesting:

The first is the fact that we appear to have Class D airspace with no control tower of any kind. For those who know anything about Class D airports they will immediately scream that this is impossible.... and they would be correct.

You cannot have a Class D airspace without a control tower, the tower doesn't have to be at the same airport (see nearby VUO for an example of that), but Class D = tower. So what gives?

Simple, the FAA airspace making beat the tower construction crew. Once the FAA decided to make a new airspace zone there is a very exacting federal process that must be followed. Once started it can't really be stopped or you get to start all over, this process takes months.

Then there is the actual construction of the facilities needed to run the tower (the tower itself and equipment). Ideally these 2 phases finish at the same time, or the tower is built before the airspace is ready (and simply isn't used until then).

The issue happens when the tower construction is delayed and the airspace wins. By law that airspace now exists and therefore must be charted (so it is), however, there isn't a tower there so no tower is marked on the chart. But what about the airspace? The FAA will NOTAM the airspace out of existence until the tower is open (if we got to this yesterday before the tower opened we'd have seen a NOTAM saying the airspace is inactive).

So not common but not unheard of.

The second point, that one is very different:

There is no such thing as a shelved Class D airspace, until today...

FAA orders that I've read don't allow this to be done, however here it is. Per the rule making notice:

That airspace extending upward from the surface to and including 2,700 feet within a 5-mile radius of Aurora State Airport, excluding that airspace below 1,300 feet beyond 3.3 miles from the airport from the 142° bearing clockwise to the 172° bearing from the airport, and the 250° bearing clockwise to the 266° bearing from the airport, and that airspace within a 0.5-mile radius of Workman Airpark, OR. This Class D airspace area is effective during the specific dates and times established in advance by a Notice to Airmen. The effective date and time will thereafter be continuously published in the Airport/Facility Directory.

That creates 2 shelves of airspace within the Class D which as far as I know is unheard of. There is no charting convention for this (which has led to the sectional charting being misleading at best), and honestly I don't understand the benefit. Either exclude it all or include it.

I don't have a neat answer for this second point. They either need to define a way to chart Class D shelves or stop doing this, otherwise you'll cause confusion.

There have been a few instances of things like this happening across the U.S. in the last two or three years.

Can you give me a couple, I'd like to look into this a bit more. We've caught this one in a hybrid state on the sectional, I'd like to see one that's been around for a while.

It's a nice option, but unfortunately the pilots at the neighboring airports that underlie the new Class D airspace are bound to at least 3SM visibility rather than the usual 1SM permitted by Class G minima.

I see the theory behind this (the old FAA definition that surface area meant all airspace extended down to the surface), however they've gone back on this:

From a 2006 FAA interpretation available here http://www.faa.gov/about/office_org/hea ... tation.pdf

The term "surface area" refers only to those components of airspace that come in contact with the surface of the earth.

That's it from me on this one, this one meets the "weird" criteria in my book.

Further reading indicates that 7S9 airport requested that the FAA raise the shelf to 1300' as opposed to 1200'. The FAA said they could not as a result of the instrument approach that exists to UAO. This might make sense. On the RNAV RWY 35 approach, the FAF at CIGRU is 1700'. That leaves 500' of protected airspace between the D and the shelf underneath.

Could this be the reason? CIGRU is only 1 mile west of the shelf. If that is true, it doesn't quite explain the western shelf.

Further reading indicates that 7S9 airport requested that the FAA raise the shelf to 1300' as opposed to 1200'. The FAA said they could not as a result of the instrument approach that exists to UAO. This might make sense. On the RNAV RWY 35 approach, the FAF at CIGRU is 1700'. That leaves 500' of protected airspace between the D and the shelf underneath.

Could this be the reason? CIGRU is only 1 mile west of the shelf. If that is true, it doesn't quite explain the western shelf.

That explains the altitude of the shelf but not why it exists in the first place.

Class D airports don't get airspace shelves, it's surface to a set altitude in the entire airspace. If this airspace were to match every other class D in the country it would be surface Class D over both those airports which have shelves.

For untowered airports there are 2 ways it's handled airspace wise. It's either ignored and put within the Class D airspace (see the multiple airports within HIOs {just to the North of VUO} Class D airspace), or a cutout is made so that there is no Class D airspace over the airport (see 7S5 near SLE {just South} which has a cutout of the Delta for it).

The way VUO is doing it (as a shelf) is a brand new procedure which has been executed poorly (how do you know the altitude of the shelf by looking at the sectional? or even what the line means at all?) In my opinion I see no benefit to inventing a new way of doing it.

This is absolutely crazy making! Shelf-ed Class Delta airspace with odd radial quadrants. No thanks.

KADS is odd enough for me with a bifurcated top - but at least the airspace is from the surface with no weird cutouts. And "satelite" airpark is handled consistently too - by contacting KADS to get in or out.

Yuck.