Aurora Airpark

So, I've been flying Yoland's Colorado Postal flights. I know, those are so yesterday, the new thing is the Anchorage Postal Flights. The thing is I can't fly these projects fast enough to keep up. I just start on a new project and Yoland posts another one. Anyhow, bear with me here.

The Colorado Postal Flights follow Yoland's standard practice. They're based out of a (usually small) airport and they make runs of 5-8 legs out and then return to the base. The Colorado Postal Flights are based out of Aurora Airpark (01V) in the Denver area. I flew the first leg out of 01V a few weeks ago and I've been off in the Colorado hinterlands since then - including an approach to the infamous Aspen airport, which is a piece of cake in good weather in a slow airplane, but not so much in a Learjet at night, but I digress.

I guess I was half asleep when I departed 01V, because I didn't notice anything unusual. I just did my usual VFR Direct thing and put the pedal to the metal. On these flights, I just worry about flying into a cloud with a solid center, so I'm focused on how far away the mountains are and how high they are. You can't count on not encountering a cloud out there, so you have to think about rates of climb and stuff like that.

So when I planned my return to 01V this afternoon (9POST276) I thought I'd take a look and see what was up with 01V. So, I typed it into the the search box at MyAirplane.com and got nothing. Hmmm. So, I went to Skyvector.com and typed it into the Airport search box. Again nothing. Funny. It's there in PlanG and in FSX, but it isn't even on the Denver Sectional anymore. I think I can see a trace of the runway on Google Earth, but all the hangars and stuff are gone. Yup, it's closed; it doesn't exist.

But, Plan G told me where the airport was, its elevation and the direction of its runways and the FSX flight planner accepts it, so it must be there - in the simulator at least. So, off I went and sure enough, my GPS led me right to it. However, as I flew the pattern to approach Rwy 32, I noticed that I was in a swarm of mosquitos, except these mosquitos were of the Boeing and Airbus genus and it wasn't clear that they were all that far above me. Somehow, I got down without a midair - another victory for the big sky theory.

That must be it, I thought. They closed this place because it's right in the landing pattern for the northbound runways at the new KDEN. So I went to Plan G to look at the KDEN Class B airspace (you can see the same thing on the sectional). Plan G has a nice feature where you can turn on the "Information box” and get airspace information as you pass the cursor over various regions of the map. I'm sure you all know what a class B airspace around a major airport looks like, right? It's like an "upside down wedding cake"; the closer you are to the airport, the lower you have to be to be outside the class B airspace. Sure enough, when I put the cursor inside the smallest ring around KDEN, it read "Class B SFC+ DENVER”. This means the airspace is class B all the way down to the ground (surface) inside this circle. So no wonder they closed 01V. Many of the aircraft which used that airport in the old days didn't have radios, so they couldn't even ask for clearance to enter the Class B airspace, not that they would have received it if they did. So I figured I'm pretty smart for a non-pilot with no history of formal flying instruction.

Well, as they say, "not so fast". This subject interested me, so I typed "What happened to Aurora Airpark" into my friendly local search engine and got a raft of relevant responses, including one piece that traced the history and ownership of the airpark from its earliest days. I won't drag you through all that, because I see your attention is starting to wander. Long story short: 01V was closed in July 2004 because the owner just didn't want the trouble and expense of continuing to maintain it. And this made a lot of local Denver pilots pretty unhappy, because they loved the place. So WTF, as they say. So I went back to Plan G and put the cursor smack on the site of 01V and the information box came up with: “Class B 6500+ Denver”. On closer inspection it turns out that the inner circle around KDEN is shaded purple, except for a couple of rectangular cutouts in the lower right (SE) quadrant and another purple circle around KBKF. The circle is Class E and Class D around KBKF (Buckley AFB) and the rectangular cutout is the ”Class B 6500+ Denver” region. I'd say that 01V is so close to the edge of this cutout that you'd have to fly left traffic on Rwy 32 and right traffic on Rwy 14 to avoid entering Class B airspace while flying the pattern. Wow! I went back and looked at my VFR Direct flight plan for the departing flight and found that it went slightly south of west and thus avoided the Class B airspace by happenstance. But the return flight I did this afternoon (9POSTY276) carried me smack dab into the “Class B SFC+ Denver” airspace and I was clueless. Of course the FSX native ATC always gives you the option to ask ATC for permission to enter the Class B airspace and you can usually see that flashing on your Garmin. But that and $3.75 will get you a latte, because there is nothing going on there that would separate you from all those nasty big airplanes. Learn something every day, as they say.

So here’s an exercise left to the student. Suppose 01V is still open and I’m flying the standard pattern altitude (1000’ AGL) and making a left traffic approach to Rwy 32. At the same time, an Airbus 330 is making an ILS approach on runway 35L at KDEN (01V is about 5 NM almost exactly due south of the threshold of Rwy 35L). What is the minimum vertical separation between our aircraft? The pilot with the closest answer will receive recognition in my next Forum post. Hint: no wonder I was sweating bullets on the approach.

Mike
<br /><br /><!-- editby --><br /><br /><em>edited by: Westcoast, Jun 28, 2015 - 10:47 PM</em><!-- end editby -->

That's pretty close Paul. On my first calculation I got 347', using a north-south separation of 5.0 NM and a glide slope of exactly 3 deg. Of course, the glide slope probably doesn't intersect the runway right at the threshold, but slightly further down the runway, but that's a small correction. This morning I looked up the Lat/Long of both 01V and the Rwy 35L threshold. 01V is almost directly south of Rwy 35L, the separation in longitude is only 0.0055 deg., equivalent to 1773' at this latitude The separation in latitude is .095 deg, or 5.695 NM. Using a 3.0 deg. glide slope, this yields 568' of vertical separation between the 01V traffic and the Rwy 35L glide slope. That's definitely not enough vertical separation to make me comfortable.

If you're keeping score at home, there's an easy way to get a quick estimate of this separation. Just remember the rule of thumb that a 3 deg. glideslope is about 320' of drop for each NM of track. So, if 01V is about 5 NM south of Rwy 35L, the GS is 1600' above the 01V runway. With the 1000' 01V pattern altitude, that leaves us with about 600' of separation. Of course 01V is 245' higher than 35L, but it's also 5.7 miles south of 25L. These two effects don't quite cancel, leaving us with 568' of vertical separation.<br /><br /><!-- editby --><br /><br /><em>edited by: Westcoast, Jun 30, 2015 - 12:14 PM</em><!-- end editby -->

That's a really interesting story. Do you remember much about why Aurora Airpark was closed?

Mike