Holding the AP/TRIM Disc Button Helps Counter a Roll Trim Runaway on the SkyWest ERJ

Outline

• Hook: in the SkyWest ERJ cockpit, a rare but serious trim runaway can test nerves and skills.

• What a roll trim runaway is and why it matters for safety and control.

• The hero action: press and hold the AP/TRIM Disc button to disconnect autopilot and cancel unwanted trim inputs.

• Why the other buttons aren’t the fix in this specific situation.

• A practical, calm response plan you can mentally rehearse.

• How CQ and KV concepts map to real-world handling of trim issues and flight control confidence.

• Quick recap and takeaways.

Roll trim runaway — what’s happening in the cockpit

Picture this: you’re cruising along, everything feels steady, and suddenly the airplane starts rolling with a mind of its own. A roll trim runaway is exactly that kind of scenario—the trim system keeps driving the aircraft toward a roll you didn’t request. On a SkyWest ERJ, your instinct isn’t to muscle the airplane into submission. It’s to regain deliberate, clean control and get back to a stable flight attitude as safely and smoothly as possible.

Trim systems exist to reduce pilot workload. They nudge the control surfaces so the airplane maintains the desired flight path with less stick movement. But when the trim system goes rogue, it can push the airplane toward an unexpected bank angle. That’s when quick, correct action matters. The goal isn’t heroics; it’s restoring manual control and then reassessing the situation with a clear head.

The star move: AP/TRIM Disc button

The button you want to press and hold in a roll trim runaway is the AP/TRIM Disc button. Here’s why it matters and what it does in one clear line: it disconnects the autopilot and cancels any active trim inputs that are contributing to the runaway. When you press and hold this button, you’re essentially pulling the plug on the autopilot’s control loop and stopping the autopilot’s attempt to trim the airplane in the runaway direction. That gives you direct, unassisted control of the aircraft again.

Think of it this way: the AP/TRIM Disc button is the safety switch that stops the system from fighting you. Once you’ve held it long enough to ensure the autopilot is disconnected and the errant trim command is halted, you can take command with the primary flight controls and bring the airplane to a safe, controlled attitude.

Why the other buttons aren’t the fix in this moment

Let’s meet the usual suspects you might consider and why, in the case of a roll trim runaway, they don’t directly address the problem:

• RUDDER TRIM Button: Rudder trim influences yaw, not roll. If the issue is a roll runaway, tugging on rudder trim isn’t tackling the root of the problem. It can complicate the coordination of turns or create unwanted yaw behavior, making stabilization harder rather than easier.

• CONTROL COLUMN Button: The control column is central to manual flight control, but pressing a button on the column isn’t the targeted remedy for a runaway trim scenario. It doesn’t disconnect the autopilot or cancel trim inputs. You’re better off focusing on the systems that can halt the runaway in one decisive move.

• ELEVATOR TRIM Button: Elevator trim affects pitch, not roll. While trimming can help in fine-tuning aircraft attitude in normal flight, it doesn’t counteract a roll-driven runaway. It may even mask the underlying issue if used inappropriately during a trim runaway.

In short, the AP/TRIM Disc button is the specific tool designed for this exact situation: disengage the autopilot and stop the trim from driving the airplane into an unintended roll.

A practical, calming response you can rehearse

Handling a trim runaway is as much about mindset as it is about procedure. Here’s a straightforward, real-world approach you can internalize:

• Stay calm and breathe. A steady tempo keeps your hands steady. The airplane will respond to your inputs; your calm reduces reaction time errors.

• Confirm the autopilot status. If the autopilot is active and the airplane is rolling, your first move is to get control back. Press and hold the AP/TRIM Disc button to disconnect the autopilot and cancel trim inputs.

• Maintain control with the sidestick or yoke. Center the control input you need to arrest the roll, keep your bank angle within safe limits, and apply coordinated rudder as needed to maintain directional stability.

• Reassess trim once stabilized. After you’ve stopped the runaway and regained control, you’ll want to re-establish a stable attitude and determine whether any trim corrections are needed. Be mindful that the immediate priority is to regain and maintain control, not to chase trim perfection in a moment of anomaly.

• Check for any messages or indicators. Once you’re safe and stable, review cockpit indications for autopilot status, trim activity, and any system fault warnings. This helps you diagnose whether the issue was a transient hiccup or something that requires further attention.

• Return to a clean configuration. Once you’ve stabilized, you can re-engage the autopilot if appropriate and restore normal flight configuration in a controlled, deliberate manner.

Bringing CQ and KV into the moment

For pilots, SkyWest-specific CQ (Cockpit Qualification) and KV (Knowledge Validation) concepts aren’t just box-checkers; they mirror real-world expectations. When you learn about roll trim behavior and the AP/TRIM Disc function, you’re building the practical mental model that CQ and KV emphasize: solid cockpit discipline, precise system awareness, and the ability to act quickly and correctly under pressure.

In practice, CQ and KV emphasize:

• System understanding: knowing what each control surface and computer does, and how they interact during normal and abnormal operations.

• Contingency readiness: recognizing the signals of a trim anomaly and applying the right fix without delay.

• Coordination and communication: coordinating with the crew, if present, and maintaining clear, concise actions and checks.

That knowledge translates directly to safer hands at the controls and more confidence in the cockpit. It’s not about memorizing tricks; it’s about building a robust mental model so you can react quickly and correctly when something unexpected happens.

A few talking points you’ll notice in real-world cockpit conversations

• The AP/TRIM Disc button isn’t just a reset; it’s a targeted action that stops a runaway system and hands the airplane back to you. It’s a reminder that the autopilot is a great helper, but when it fights you, you take the reins.

• You’ll hear the cadence of a calm, procedural approach: identify, disconnect, regain control, reassess, and reconfigure. That rhythm matters as much as the specific button push.

• The difference between roll control and pitch control becomes obvious here. In a roll runaway, you’re not chasing a pitch fix; you’re taming a roll and reestablishing stable bank.

Putting it all together: what this means for SkyWest ERJ pilots

The ERJ family from SkyWest is known for its solid handling, resilient systems, and pilots who stay composed when the unexpected shows up. A roll trim runaway isn’t something to panic about; it’s a scenario that tests your system literacy and your ability to apply a clean, decisive solution. The AP/TRIM Disc button is the precise tool for this moment, designed to interrupt the autopilot’s trim-driven motion and let you steer with your own hands again.

If you think about CQ and KV learning as a map of the cockpit’s real-world logic, you’ll see how each maneuver, each control input, and each checklist item fits into a larger picture. You’re not just memorizing what to push; you’re building a mental toolkit you can rely on the next time a weird rotor of a trim system starts to tug the airplane in a direction you didn’t choose.

Final takeaway

Roll trim runaway is a rare but serious situation that calls for calm, deliberate action. The AP/TRIM Disc button is the targeted remedy, because it disconnects the autopilot and cancels rogue trim inputs. The other buttons don’t address the root of the problem in this specific scenario, so they aren’t the primary tool here.

In the end, what matters most is your readiness to recognize the situation, apply the correct fix, and restore solid, controlled flight. That readiness—rooted in a solid understanding of the aircraft’s systems and reinforced by CQ and KV-aligned knowledge—keeps you and everyone on board safer, even when the skies throw a curveball.