Page 34 - June22Tv2

Confirmation Bias
“November three nine six delta mike, main- tain runway heading, cleared for takeoff
runway one five.”
It was a totally routine departure. “Power set, airspeed
alive both sides, 70 knots, V1, rotate” – you know, all the usual stuff. I glanced at the after-takeoff checklist to make sure I hadn’t forgotten something.
“TRAFFIC, TRAFFIC!” came the unexpected bark from the Garmin avionics suite. That interrupted my flow as I focused my total attention on a possible plane in my path. That’s part of life in the large city of “Big D.”
Climbing out of the upper twenties, I was in for a surprise.
“CABIN ALTITUDE, CABIN ALTITUDE” blared through the overhead speaker along with several big red master warning lights. “What in the world,” I said out loud as I came to grips with exactly what was happening. The memory item was to don the oxygen mask first and then resolve the problem. I did just that and then glanced at the cabin altitude indicator.
It was above 10,000 feet and climbing. “How can that be,” I wondered as I transmitted to Center that I was declaring
On Final
by David Miller
an emergency and commencing an immediate descent. Traffic was cleared away from me as I put the airplane in a steep dive to stop the rapid increase in cabin altitude.
Minutes later, I had regained my composure, landed at the closest suitable airport, and phoned the number that Center had given to me.
What in the world had ruined my day?
As I glanced around the cockpit, I finally saw it. The pressurization selector was set to OFF instead of BOTH! The airplane had just come out of maintenance, and someone had rotated the selector 180 degrees to the OFF position.
Now that I have your attention, this incident didn’t actually happen to me. It certainly could have. But it did happen to CJP’s former Chairman Marc Dulude, and he was kind enough to share it on a “What Good Looks Like” video (“Flight after Maintenance”) viewable at citationjetpilots.com/safety.
Marc had experienced confirmation bias, defined as “the tendency to interpret new evidence as confirmation of one’s existing beliefs or theories.” As Marc explains in
the video, he expected to see the pressurization selector in the BOTH position because that’s where it always was. And even though he made an extra effort to check every switch after maintenance, this one slipped by.
From the pictures, you can see how easily this can happen.
To make matters worse, his normal after- takeoff pressurization check was interrupted by the “TRAFFIC TRAFFIC” warning.
Marc is another one of the generous members of CJP who have shared their experiences so that others can avoid them. Thanks, Marc.
Fly safe.
David Miller has owned and flown a variety of aircraft from light twins to midsize jets for more than 50 years. With 6,000 plus hours in his logbook, David is the Director of Pro- grams and Safety Education for the Citation Jet Pilot’s Safety Foundation. You can contact David at davidmiller1@sbcglobal.net.
32 • TWIN & TURBINE / June 2022