The FAA has issued an Emergency AD aimed at keeping A220 pilots from hitting the wrong button by forbidding them from hitting what they incorrectly think is the right button. The AD addresses an issue with the panel of the Bombardier-designed airliner that makes it possible to engage the autopilot when the intent is to engage the autothrottle. Transport Canada issued its own version of a similar AD earlier this month after hearing of 38 incidents in which crews have inadvertently hit the autopilot button while aiming for the autothrottle button. Two of those incidents were “nearly catastrophic” because they happened on the takeoff roll and the autopilot commanded the aircraft to pitch up before V1. That’s why the A220 aircraft flight manual (AFM) prohibits engaging the autopilot below 400 feet AGL.
But the AFM does not prohibit trying to re-engage the autothrottle (turbulence can knock it off), probably because the autothrottle won’t re-engage above 60 knots and below 400 feet. That apparently doesn’t stop pilots from trying. “In September, 2022, there was an incident in which the autothrottle disengaged during takeoff and when the flightcrew attempted to reengage the autothrottle they mistakenly engaged the autopilot which resulted in the aircraft rotating below the V1 speed,” the AD says. “This resulted in a low energy takeoff which is extremely hazardous as it could lead to the airplane stalling and/or impacting terrain.” The AD attempts to address that kind of confusion by adding a note to the AFM “prohibiting selecting or reselecting autothrottle after the thrust levers are advanced to the takeoff setting until the aircraft is at or above 400 feet above ground level.”
Would not it be wiser to relocate these buttons instead? At first reading this confused me!
There’s no reason to change power on the takeoff climb before 400 feet. If the power levers are in the notch, re-engaging the auto throttle isn’t going to do anything.
Also, maybe the autopilot button should be inhibited with weight-on-wheels…
Inhibiting the AP through the WOW switch sounds simple, but it also introduces a potential failure mode where a faulty WOW switch could lead to AP disconnects or complete loss of the AP functions.
And yet apparently the AT won’t reengage above 60kts and below 400 agl, so it seems like the AP could be programmed to also not engage below 400 agl.
The autopilot relies on dozens of sensors, any one of which could fail. The WOW switch also controls many other systems on the airplane.
In the highly unlikely event of autopilot failure, I suggest that the pilots use the wheel thingy in front of them to FLY THE AIRPLANE!
There is no “notch” on the A220. They are fluid, full motion similar to Boeing. The 777 had a similar issue. A new 777 captain that came off of the 767 had a near catastrophic event. To engage the A/T on the 767, they push an EPR button for the prescribed TO power. He pushed AP engage right next to it. While the 777 didn’t have the EPR button, the 777’s buttons looked similar…OLD HABITS. When the FO, who was flying, tried to rotate, the aircraft went…”Uh…NO!” The nose wheel actually flew over the dip in the runway! The FO, seeing the construction trucks at the other end getting larger by the split second yanked it off the ground. The AP disengaged and they shot up like having been catapulted off of an aircraft carrier. British Airways had the same thing but Boeing ignored it until the US carrier had the event and threatened to ground its 777’s at Boeing’s expense!
If you follow the FAA link, search for “2022-25-51”.
This may have occurred on a recent Delta flight out of Atlanta where the crew believed it was a trim control issue. Hitting auto pilot will create what looks like a trim runaway during takeoff if you hit the wrong button. They almost lost control, but returned safely.
Will THEY (He She Him Her It Us Them Alien) ever figure out that airplanes have pilots, and autos have drivers?