In May of this year, I had an opportunity to go with a group and receive a tour of the Denver TRACON. Security makes getting a Center, TRACON or tower tour increasingly difficult, but I have done it several times dating back to my first tower visit (VNY) in 1965, and I think it is worth the effort. It is fun, educational, and can enhance safety by allowing you to spend time in the shoes of the guy or gal on the other side of the frequency. My Denver TRACON visit was no different: I learned stuff, had a great time, met some wonderful people… and got an interesting safety lesson that I would like to relate here.
During its briefing to us, the TRACON raised a concern that they have been contemplating. It turns out there are situations where an airliner in the Class B airspace is cleared for a visual approach, and the airliner’s response includes descending below the floor of the Class B airspace. They had even prepared a briefing slide in PowerPoint to show our group a specific instance where a GA aircraft had come to within just a few hundred feet of an airliner due to this issue.
In the image, one can see the airliner (red) approaching for a visual approach on 35R at DEN. The GA aircraft (green) departs FTG heading for APA. The GA guy remains below the Class B airspace at 6,800 MSL. When he observed the airliner right in front of him descending through 7,000, which is well below the floor, he climbed to avoid, apparently the only thing that kept this incident from becoming a tragedy.
I was amazed that the TRACON chose to share this information with us. They went on to mention that they had spoken to the airlines about this issue and this incident. They told us that the airlines to whom they spoke said first that they had no information in the cockpit on the floor of the Class B airspace! They also said that this “dive and drive” maneuver to get down low during a visual approach was common.
A friend amplified on this, saying specifically that Airbuses are difficult to slow down and many crews manage this by getting to a set altitude and flying level while slowing to the landing configuration. Finally, I think the TRACON felt there is ambiguity in 91.131(a)(2) wherein a visual approach is perhaps taken as authorization from ATC to operate below the Class B floor. (Its text: “Unless otherwise authorized by ATC, each person operating a large turbine engine-powered airplane to or from a primary airport for which a Class B airspace area is designated must operate at or above the designated floors of the Class B airspace area while within the lateral limits of that area.)”
I decided to mention this on my Facebook page. I was stunned at the apparent disregard for safety and the regulation. I wanted to know what some of my airline pilot and other pilot friends would think. I can tell you that I am impressed and pleased with the discussion and the answers I received. Maybe it’s even evidence that Facebook is a good collaboration tool!
- One of my friends said he knew a number of crews who dive and drive, and he had several reasons they raise for doing so, but he recognized that a 3 degree glideslope (at least on this approach in Denver) is manageable and safer.
- A second friend showed my other colleagues where to find the information on the floor of Class B airspace in their Jeppesen charts, namely section 10-1B. At least some of them were not previously aware that this information was available to them at all!
- A third friend vowed to take the information to her airline to make them more aware and increase safety airline-wide.
- A fourth friend was able to show the rest of us information on new charting that is “in beta” (to be published soon) including improvements using color that make much clearer the information needed to avoid a 91.131(a)(2) transgression, otherwise known as a Class B Airspace Excursion. This means, in part, that those responsible for charting were already aware of the need for improvement and are acting on that need.
In summary: I am privileged to have some wonderful and safety-conscious friends. They and the rest of the airline and ATC community are becoming aware of the threat and are taking steps before the disaster to avoid it entirely. Nonetheless, a safety tip: if you regularly drive around under the floor of your local Class B, I recommend you become aware of where the usual visual approach corridors are so that you can exercise caution and remain vigilant for traffic. It’s always good to see them coming so that it ain’t even close.