Career Pilot: Class B Dropouts

So you’re cruising around underneath the Denver Class B airspace when—hello!—you find yourself staring face to face with a Boeing 757. You make an evasive move and you notice the big Boeing also is reacting, most likely in response to a traffic collision avoidance system (TCAS) resolution advisory. After regaining separation, you double-check your position on your iPad or chart and verify that you are certainly underneath the appropriate sliver of airspace. So what happened?

Class B excursions, also known as “dropouts,” occur when large or turbine-powered airplanes operating to or from the primary airport for which Class B airspace is designated fail to operate at or above the designated floors of that airspace. This is spelled out in FAR 91.131, and it has become a problem for airline flight departments and air traffic controllers (ATC). How bad is it? According to FAA statistics, there were 10,600 Class B excursions in 2016 at Denver International alone. And nearly every major airport with associated Class B airspace experiences such excursions every day.

The moral of the story? Sometimes GA pilots are not the problem, which is good news from a legality standpoint but not from a safety perspective. In this case, it’s the pilots of the big boys and ATC who are screwing up. How does it happen? In many cases, the visual approach is to blame. In other cases, it’s the premature issuance of a descent clearance by ATC to an airliner, or perhaps a last-minute extension of the downwind that has a jet fly out of a segment of the Class B and under a higher shelf. As with many things in this dynamic operating environment, mistakes do occur.

The biggest threat comes from the visual approach. The visual approach is usually a win-win for both pilots and controllers. It frees ATC from providing vectors and subsequent IFR approach clearance while pilots are given the freedom to get to the runway, mostly on their own terms. Unknowingly, professional pilots are sabotaging themselves if they accept a visual approach without verifying that they remain within the Bravo.

As an airline pilot, I and many of my colleagues have been ignorant victims of this trap. Once cleared for the visual approach, pilots may use a dive-and-drive method to get to the final approach fix, oblivious to the fact that they may be dropping out of the Class B. In other cases, I’ve seen ATC attempt to direct us below the floor of the Bravo while we’re still flying 250 KIAS. Recall that the speed limit below the floor of Class B airspace is 200 KIAS.

In the all-IFR environment of professional flying, many professional pilots haven’t looked at a VFR chart in years—or decades. Yes, Jeppesen includes a Class B airspace chart with charts of the main airport in Class B airspace, but without the boundaries being depicted on our displays, it can be a cross-referencing challenge to determine your exact location while you’re already in the high-workload approach phase of flight. Although GA pilots have amazing apps that can display your position on a VFR sectional chart, airline pilots don’t yet have that ability.

Likewise, the fancy apps have allowed GA pilots to confidently go up to the borders and floors of Class B, which many were hesitant to do in the pre-moving-map days. No longer is there a buffer zone that ATC can count on. I’m guilty of it too, when I fly my Cessna 172 equipped with Garmin Pilot recreationally near Baltimore-Washington International. I am, however, talking to ATC and keeping a sharp eye out for the parade of arrivals above me.

What’s the solution? Airlines are already making pilots aware of the issue and, in the case of my airline, training has already occurred. In reality, however, it will take time for professional pilots with years of ingrained habits to fully grasp the issue. Perhaps the most important technique professional pilots can use is to maintain altitude until absolutely necessary to descend to arrive at the final approach fix at the appropriate altitude. No more diving and driving. Jeppesen, which now has Class B boundaries on many of its approach charts, is being lobbied to add altitudes to make it much easier for pilots to cross reference Class B floors without having to consult a separate chart.

In the meantime, maintain your vigilance when operating at or near the boundaries of Class B airspace. Most GA airplanes don’t have TCAS, so there will be no collision warning like what pro pilots get. Equipping with Automatic Dependent Surveillance-Broadcast (ADS-B) will help, but it’s not a complete solution. Obtain flight following whenever possible as well. Class B dropouts may not be your fault, but the results can be catastrophic, so stay vigilant.