Cessna Citation Crash--Downed by Pushing the Wrong Autopilot Button?

The 2007 crash of a Cessna Citation flying a University of Michigan medical team may have resulted from the wrong push of a button by the copilot. So says an article in yesterday’s Detroit Free Press. While the final NTSB report has not been issued, preliminary data points in several directions including the possibility that the copilot turned on the autopilot instead of the yaw damper shortly after takeoff. According to one source, “the two buttons are next to each other on the center console, and some aircraft manufacturers have redesigned cockpit controls in recent years to avoid such mistakes.” The plane crashed in the water a few minutes after takeoff from Milwaukee, WI.

The preliminary or factual NTSB report states:...

"Recordings retrieved from the airplane's cockpit voice recorder contained comments by the Captain, who was the flying pilot, that he was ‘fighting the controls’. The first indication on the recording relating to ‘fighting the controls’ occurred about 18 seconds after the FO called out ‘rotate’, 11 seconds after the Captain called for the yaw damper, and less than one second after the FO acknowledged a turn to a heading of 050 degrees. Later in the recording, the Captain is heard to say ‘something is wrong with the trim’; ‘I'm fighting the controls. It wants to turn left hard’ and ‘…she's rolling on me. Help me help me.'"

According to the Detroit Free Press, multiple factors are being investigated. “Of the six NTSB teams, one is questioning whether the two-man crew should have been in the air in the first place. The pilot had a criminal conviction that an FAA inspector didn't question, and the copilot previously had crash-landed a plane after ‘he inadvertently took off with the electrical generator switches in the 'off' position and subsequently used an improper emergency gear extension procedure,’ according to an NTSB investigative report last year.

"Yet another team, focusing on the plane's airworthiness, has been examining chafed and melted wires and the plane's wreckage. They've discussed the issue of faulty circuitry that was not replaced, despite a 1992 service bulletin about concerns that flat-ribbon wires were bundled too tightly and might short-circuit."

Check Autopilot Status Indicators after Every Button Push
While it’s too early to know if pushing the wrong button doomed this flight, it’s entirely plausible. One of the most common errors I see pilots make is pushing the wrong button on the autopilot. In fact, my biggest pet peeve is pilots who don’t know how to operate the autopilot but continue to stab away at the buttons until they think they’ve finally pushed the right ones!

Another common error is that pilots don’t check the autopilot status indicators after each button push to confirm that the autopilot is in the state they think they’ve set. This is particular a problem for those autopilots where the status indicators are located separately from the buttons, such as some versions of the Garmin G1000 and Perspective. Since some keys have a toggle function—the same key can produce two different states—it’s impossible to know what state the autopilot is in unless you check the status indicators. For example, the HDG key might be used for both heading mode and ROL (wings level) mode. Often pilots push the HDG key to get the heading mode but set ROL mode instead. Then they don’t understand why the airplane isn’t following commands from the heading knob.

In the case of the doomed Citation, if the copilot did inadvertently turn the autopilot on and the pilot didn’t realize that, then he set up a very dangerous situation. For most autopilots, only the autopilot or the pilot can control the plane, not both. When the autopilot is on and a pilot pushes or pulls on the controls, the autopilot will begin trimming in the opposite direction from the pilot’s control inputs. Thus if the pilot pulls back to climb, the autopilot will trim nose down to make the aircraft descend. In most cases, the autopilot will continue trimming until it reaches the stops, creating control forces that may exceed a pilot’s physical strength needed to operate the controls.

It's well worth your time and money to get good instruction from a flight instructor who thoroughly understands the autopilot in the aircraft you fly. Also, when using the autopilot, remember to read the status indicator after each button push. Finally, if you ever get into a life and death struggle with the autopilot, you will win that battle—if you remember to pull the autopilot circuit breaker.

Comments

[Vincent, from PlasticPilot.net]

Your raise some good points Max and I want to add some others regarding autopilot design and procedures. I flew a lot with the KFC 150, which has no toggle modes, except for the NAV intercept. I also like the KFC way of activating modes before engaging the autopilot.

I don't really like the KAP140 because you must first engage it and them program it. Any mistake will bring you in an unwanted maneuver immediately.

And this brings me to the last point: flight director. With the KFC150 and almost all flight director autopilots, the flight director comes in view when a mode is selected, before autopilot engagement. This makes possible to visualize what the autopilot wants to do before engaging it.

My routine for the KFC150 was always: Modes - Check FD - Engage. No way to do that with a KAP140.

Had this Citation a flight director ?

[Matthew Stibbe]

I had a partial fail on my IR checkride because I pressed the altitude button on the Cirrus but didn't press it hard enough for it to engage and didn't check. Result: a gentle descent below the approach path and a re-take the next day. Ouch!

Luckily I had a very experienced examiner with me who was not wearing foggles and not under extreme stress!

The moral of the story, at least for me, is similar to Vincent's (Hey, Vincent! how come you always comment before me!): press and check. Press and check. Press and check.

Just like the drill they taught me for using a VOR: select ident and display, it makes sense to have a mini-checklist for autopilots. Especially in the Cirrus where you may or may not have a FD, a Garmin or an S/Tec a/p plus if it's an S/Tec you have to engage it in a specific way.

[Charles Scott]

I am a CFI and I know the captain's daughter. She has been terribly upset about the gratuitous info but I have had a few hours in Citations and know how hard it is to see some switches. I stopped flying when I went into bifocals. Just too many things can happen in IFR and bumpy conditions. Now I rent a 210 once in a while. I'll tell Jenn I read this article.