There are still a few control towers in the United States that operate like airfield bonfires did 75 years ago. These are the VFR control towers: they are classified as Class D Airspace.
THE VFR TOWER
Despite its official name, a VFR tower can handle IFR traffic, and relay IFR clearances to instrument pilots. It is called a VFR Tower because it has no radar installation of its own. Some have a “repeater” scope, but that’s just a monitor of someone else’s radar screen. Mostly they look out the window and use binoculars to spot traffic. Often the controllers who work the VFR Tower are not FAA employees. There will be a notation on the sectional chart that says “NFCT” which stands for Non Federal Control Tower. Most of these were FAA towers at one time, but budget cuts or shifts in traffic load sent the FAA packing… the tower stayed behind. Local airport authorities and communities did not want an empty control tower sitting there, so they hired their own people to operate the VFR Tower.
CLASS D AIRSPACE RULES YOU SHOULD KNOW
First of all, Class D is controlled airspace from the surface up. That means VFR flight within the Class D airspace requires three miles visibility during the day. VFR flight in Class D with less than three miles visibility, but greater than one mile, would require a Special VFR clearance.
The airport symbol is blue, which signifies that the airport has an operating control tower at least part of the time.From the Chart: Look at figure 1 of Owensboro, Kentucky.
- The control tower frequency of 120.7 has a star beside it, which indicates that this control tower does not operate 24 hours a day. Pilots must check the Airport/Facilities Directory for the exact open and closed times.
- The airport is also ringed with a blue dashed line. The blue dashes tell you that Class D Airspace will be in effect anytime the control tower is open.
- Inside the blue dashed line there are bracketed digits, ‘.’ The “” is a code that tells how high up the Class D Airspace goes: in this case, 2,900 feet MSL (approximately 2,500 feet AGL). So the Class D airspace is cylinder shape and begins at the ground and ends at 2,900 MSL.
CLASS D OPERATIONS/COMMUNICATIONS
The control tower operator at a Class D airport cannot see you coming on radar (remember, they don’t have radar). Therefore, you must communicate with the control tower operator to take off, to land, or to fly through the Class D cylinder. You would only be required to communicate with the tower prior to entering the blue dashed circle. You might say, “Owensboro Tower, Cessna 1234A, eight south, inbound for landing.” The tower controller might respond with, “Cessna 1234A, visibility is 6 miles, enter and report left downwind for runway 18.”
Translation: The controller cannot see you, so he clears you into the blue dashed circle, and asks you to report at another location where he probably will be able to see you: left downwind. When you enter and report the downwind, chances are good the controller has you in the binoculars and when you say, “Owensboro Tower 34A left downwind to runway 18,” the controller will say, “34A you are cleared to land runway 18, wind is 170 at 10.’
If you did not want to land at Owensboro, but were flying through the area, you have several other options. You could either fly over the Class D Airspace at an altitude higher than 2,900 feet, fly around the blue dashed circle, or talk to the tower and get a clearance to “transition” through the airspace.
…MORE CHART WORK
Now look at the airspace symbols around Owensboro (figure 1) again. In addition to the dashed blue circle around the airport, there are dashed magenta extensions attached. These extensions are areas where Class E Airspace comes down to the surface. You can see that these extensions are aligned with the runway — they provide inbound IFR traffic with a descent corridor for instrument approaches to these runways. The Class E allows them to remain in controlled airspace to the ground. But the “effects” of the magenta dashed extensions only come into play when the visibility is less than 3 miles. When the visibility is less than three, these extensions, and the blue dashed circle within, become off limits to VFR traffic, allowing safe passage for IFR traffic to descend through the clouds and into the airport. But, when the visibility is greater than three miles, VFR pilots can fly into the magenta dashed area without clearance.
Important: Remember that the dashed blue circle lies within and VFR pilots must communicate with the control tower before entering — regardless of the visibility. At some airports the blue dashed lines surround the airport and make up the extensions. In that case a pilot, IFR or VFR, would have to communicate with the tower before entering either the inner circle or the extensions. In our example at Owensboro, the extensions are magenta, so VFR pilots flying with greater than three miles visibility can fly through the extensions without contacting the tower.
BOTTOM LINE: When the control tower is open, Owensboro is an example of a controlled airport in controlled airspace. Controlled airports and controlled airspace are not the same. Controlled airports have tower controllers who must grant permission to land, take off, or transit their area and this permission is required regardless of weather conditions. Controlled airspace, on the other hand, depends on current weather conditions and if a weather observer is present to judge visibility and ceiling. Two weeks ago we looked at an example, Somerset, Kentucky, where controlled airspace was present at a non-towered (uncontrolled) airport. Can you ever have a controlled airport inside uncontrolled airspace? Yes! We look at this case next week…