What is a Class B airspace excursion?

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.

Class B airspace
You’re under the Class B shelf, but are you under the airline traffic?

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.

6 Comments

  • You mention “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. …” in the article, but the lone image published with the article just shows Bravo shelving, seemingly unrelated to the description.

  • I remember while flying in the late 70’s and early 80’s around the old Pittsburg airport that the big guys would flash their light when they saw you and I in my Tri Pacer would do likewise. Folks from my airport said happens all the time, airliners below in VFR keeping watch for everyone. I am not IFR but when they are cleared for the visual approach, are they still flying IFR?

  • Out of curiousity, does anyone know if 91.131(a)(2) applies to scheduled airliners (which operate under part 121, right)?

    Not suggesting that the behavior is prudent, but is it clear that it’s a violation of that rule? I realize that I don’t have a good understanding of how Part 91 and part 121 tie together.

  • Good observation Jim. I have been complaining about this very subject for years. There is plenty of blame to go around. The problem begins with the pilot’s mentality that an IFR clearance somehow makes neighboring VFR operations insignificant and a Visual Approach CLEARANCE somehow means the pilot is free to do as he/she pleases. That is a fatal mistake. Remember the B727 v C172 incident in SAN, 1978 ? (b.y.b: that incident led to the creation of the SAN TCA). I don’t know of a single IFR pilot flying with a TAC on his/her knee.

    So how does an IFR pilot (and in particular, those flying big iron under 121 & 135) comply with 91.131(a)(2) ? By doing him/herself and the world a big favor by NEVER accepting a Visual Approach clearance when offered. The temptation is not worth the consequences.

    Now, before all you experts swivel yourselves into vertigo, consider the purpose of Class Bravo airspace. It’s all about CONTAINMENT. Yes, although a Visual Approach clearance permits you to find your way to the runway entirely at your heading & altitude discretion, it does NOT permit you to violate 91.131(a)(2) & 91.117(c). Common sense dictates compliance is for your safety. You are NOT the only one out there !!!

    Flying the profile of a published IAP will keep you contained within Class B and, incidentally, just may help to keep you proficient. Not to mention, taking you to where you really want to go in the first place i.e: Branson, Rapid City, Tampa, etc. Such a deal !

    ATC is does not get a pass either. Below is an excerpt from the 7110.65W Air Traffic Control bible, para 7-9-3. An IFR arrival into a Class B primary airport will NOT get the chance to drop below the BRAVO floors unless ATC issues that Visual Approach clearance. Since ATC is in the best position to maintain the “big picture” and has the luxury of those BRAVO rings overlayed front and center onto his/her screen, I expect ATC to comply with it’s own mandate and take better care of it’s traffic by preventing that possibility in the first place.

    Note the last sentence: “Such authorization should be the exception rather than the rule.”

    7−9−3. METHODS
    a. To the extent practical, clear large turbine
    engine-powered airplanes to/from the primary airport
    using altitudes and routes that avoid VFR corridors
    and airspace below the Class B airspace floor where
    VFR aircraft are operating.
    NOTE−
    Pilots operating in accordance with VFR are expected to
    advise ATC if compliance with assigned altitudes,
    headings, or routes will cause violation of any part of the
    CFR.
    b. Vector aircraft to remain in Class B airspace
    after entry. Inform the aircraft when leaving and
    reentering Class B airspace if it becomes necessary to
    extend the flight path outside Class B airspace for
    spacing.
    NOTE−
    14 CFR Section 91.131 states that “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.” Such
    authorization should be the exception rather than the rule.
    ———
    When we consider the practical application and very real consequences of paragraphs 7-4-1, 7-4-2 and 7-4-3; ATC really isn’t doing anyone any favors with the CONVENIENCE of the Visual Approach clearance.

    Go to FAA.gov and search for 7110.65W You can download it in .pdf It is authored by the same Air Traffic Organization (ATO) people that authors our AIM. Very few of them are pilots.

  • Is a jet on visual approach issued traffic advisories by ATC? Flying near Denver I’m constantly dealing with Class B and have fly under a shelf to get just about anywhere. This issue was never mentioned during my flight training and now that I realize we share airspace it’s just a little scary. I will say the ADS-B traffic depiction helps a lot and now that I have ADS-B out it’s even better. Still a large concern.

    • 7110.65W

      7−4−3. CLEARANCE FOR VISUAL APPROACH

      c. Clear an aircraft for a visual approach when:

      1. The aircraft is number one in the approach sequence, or

      2. The aircraft is to follow a preceding aircraft and the pilot reports the preceding aircraft in sight and is instructed to follow it, or

      NOTE−
      The pilot need not report the airport/runway in sight.

      3. The pilot reports the airport or runway in sight but not the preceding aircraft. Radar separation must be maintained until visual separation is provided.
      ——-
      In other words, ATC is effectively “off the hook” concerning collision avoidance and obstruction clearance when an IFR pilot ACCEPTS a Visual Approach clearance.

      Does that make you feel any better ?

      It never ceases to amaze me just how many IFR pilots have no idea exactly what protections they are actually forfeiting when they accept a Visual Approach clearance.

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