During an initial AC test on the SkyWest ERJ cockpit, keep the AC supply on.

Outline at a glance

• Opening how and why early electrical checks matter for Skywest ERJ CQ and KV scenarios

• The core question: which action is permissible during an initial AC test?

• Why Maintaining AC supply is the correct move

• What happens if you do something else (hydraulic pumps, cycling FCM switches, powering down)

• A practical, crew-friendly way to run the initial AC check

• Real-life connections: how this fits into broader cockpit readiness

• Common slip-ups and quick reminders

• Wrap-up: the mindset that keeps tests reliable and safe

Keeps the lights on: understanding the initial AC check for Skywest ERJ CQ and KV

Let me explain something simple, yet crucial. In the Skywest ERJ world, the moment you start an initial electrical check, you’re not just flipping a switch. You’re setting the stage for every system you’ll rely on in the cockpit—avionics, flight controls, navigation, communications, and the environmental controls that keep the cabin comfortable. In CQ and KV scenarios, the first pulse of the test is all about stability. If you disrupt the environment you’re trying to measure, you’ll get noisy data, unclear fault indicators, and a constant risk of misdiagnosis. So, what action is permissible? Maintaining the AC supply. That single, critical choice helps you observe how power distributes to essential systems without the test being skewed by other ongoing actions.

Keeping the AC supply on isn’t a flashy move. It’s like keeping the lights on while you test the wiring. You want to verify that the electrical system is healthy under normal operating conditions. When the AC power is steady, you can observe voltage levels, confirm that buses are energized, and check that essential systems stay active as intended. It’s the quiet baseline you need before you begin to interpret anything else.

Why Maintaining AC supply matters

Electrical power in the ERJ is organized with buses and routes that feed different system groups. There’s a reason the checklist guidance emphasizes keeping the AC supply on during the initial test. Here’s the practical logic:

• Consistency for measurements: If power fluctuates or drops during an initial check, the readings you collect won’t reflect the true state of the airplane’s wiring under normal operation. You’ll be chasing ghosts—faults that aren’t real or missing problems that actually exist.

• Verification of essential systems: The initial AC test is meant to confirm that the core flight deck and aircraft systems receive reliable power. That includes critical avionics, flight instruments, communication gear, and primary flight controls’s baseline functionality. You want those to be behaving as expected before you proceed.

• Safe test environment: When AC is maintaining, you avoid the unintended side effects that can occur if a pump starts pumping, a switch toggles a new status, or a system powers down. The airplane isn’t wrestling with multiple simultaneous inputs—it’s a controlled test, with predictability built in.

What about the other options? Let’s look at the three commonly tempting actions and why they’d complicate the test:

• Running any hydraulic pump (Option A): A hydraulic pump is a heavy system load. If you start a pump during an initial AC check, you introduce a shift in power demand and a cascade of potential interactions. Hydraulics can indirectly affect flight controls and actuation systems, which may muddy the test data and make it harder to tell what’s happening with the electrical side. You’d be chasing a moving target rather than getting a clean read on the electrical baseline.

• Cycling FCM panel switches (Option C): The FCM (Flight Control Module) panel is tied to status indicators, control logic, and sometimes displays. Cycling switches can create fluctuations, spurious alarms, or changes in the status of subsystems that aren’t related to the intended initial assessment. It’s easy to misread the results when the panel is jittery from a switch flip, so this action is best saved for a later, more controlled step in the sequence.

• Powering down the system (Option D): This one is a no-go for the initial test because the objective is to verify how the AC power feeds the airplane in a live state. If you power down, you’re defeating the purpose of the test, which is to observe how systems perform with power present. Rebooting or restarting under testing conditions can mask issues or create a false sense of stability.

A practical, crew-friendly way to handle the initial AC check

Here’s a clean, straightforward approach you can picture in your head when you’re moving through CQ and KV scenarios. It’s not about memorizing a wall of steps; it’s about maintaining a steady, deliberate rhythm.

• Step 1: Confirm power sources. You’re looking for consistent AC input from engines or APU and a stable external power source if one is used. Check the indicators or meters that show AC availability, voltage range, and frequency. You want an environment where the AC supply stays within specified limits.

• Step 2: Verify essential bus energization. Make sure the essential and non-essential buses come alive as designed, and that indicators show normal status. This is your baseline sanity check, the moment where you say, “Okay, power is feeding the heart of the system.”

• Step 3: Scan for fault indications. Look for any alarms, cautions, or abnormal messages in the cockpit displays or EICAS-style annunciations. If something looks off, you note it, but you don’t alter the power state yet. You’re not chasing a fix—you're confirming the baseline.

• Step 4: Observe stability. Give the system a moment to settle and watch how the indicators behave. If everything remains steady, you’ve established a reliable starting point for the rest of the CQ and KV steps.

• Step 5: Document and communicate. Record the results clearly, noting voltages, frequencies, and any anomalies (even if they’re minor). Share with the team so everyone has the same reference for the next actions.

A few practical tips to keep the flow smooth

• Use a calm, consistent tempo. The first AC test is a moment for careful observation, not rapid button-mashing. A deliberate pace reduces errors and makes the data easier to interpret later.

• Talk through what you’re seeing. A quick inner narration—“AC is steady; bus A is energized; no faults so far”—helps keep you connected to the data and makes it easier for your crewmate to follow.

• Keep it simple. You don’t need to chase every potential issue during this first step. The aim is to verify a stable power baseline, not to diagnose every subsystem at once.

• Trust your indicators. If the gauges or displays are within the expected ranges and there are no fault warnings, you’re likely in a good zone to proceed to the next steps in the CQ and KV sequence.

• Be mindful of the bigger picture. Electrical stability under test conditions often ties into how the aircraft will behave in more dynamic situations later on. A solid foundation now saves a lot of back-and-forth later.

How this mindset fits into CQ and KV readiness

Think of CQ and KV as a cockpit-ready repertoire, where each module complements the others. The initial AC check is less a single maneuver and more a trust-building exercise. When you maintain AC supply, you’re validating that the airplane is ready for the more nuanced checks that come next—things like verifying navigation database integrity, testing communication channels, or confirming flight-control system responsiveness under controlled conditions.

In practical terms, this means you’re not just ticking boxes. You’re cultivating a mental model of where the airplane sits in terms of power distribution, where the potential fault lines could lie, and how those faults might manifest under load. That awareness translates into quicker, safer decisions when you’re navigating the real flight rhythm or when you’re confirming the KV knowledge under pressure.

Common slip-ups and a quick relief plan

• Getting distracted by minor flickers and calling them faults: Remember, an initial check is about steady-state performance. If a small dip is within spec and then stabilizes, it’s likely not a showstopper for this stage.

• Neglecting to note the baseline before moving on: A missing datum point makes later comparisons hard. If you’re ever unsure, write it down and verify with the team.

• Letting other actions sneak in at the same time: Resist the urge to “quickly test one more thing.” The integrity of the baseline is fragile—turs and flares in the data come from mixing actions.

A quick, human reminder: you’re not alone in this

The cockpit environment rewards calm, disciplined thinking. The initial AC test is a shared moment among the crew to establish confidence in the aircraft’s electrical backbone. It’s the kind of step that feels small, but its effects ripple forward—so the approach matters as much as the outcome. When you maintain AC supply, you’re setting a steady stage for everything that follows, and that steadiness is exactly what CQ and KV scenarios are designed to measure.

Connecting the dots with real-world nuance

If you’ve ever watched a pilot describe how a light switch doesn’t just illuminate a room but also signals a chain reaction through the entire electrical system, you’ll understand the balance at play. In aviation, even tiny decisions—like preserving a power baseline—have outsized consequences. The initial AC test isn’t glamorous; it’s practical. It’s the moment you show you understand the architecture: power comes first, then perception, then action.

In the end, this approach also reflects the broader philosophy behind CQ and KV modules: a strong foundation makes everything else possible. When the AC supply stays steady, you can move through the rest of the scenarios with a clearer head and better situational awareness. You’re not just testing the airplane; you’re building the habit of precision, safety, and clear communication—the kinds of habits that keep crews cohesive and operations smooth.

A concise recap

• The permissible action during the initial AC test: Maintaining AC supply.

• Why this is the right choice: it preserves a stable baseline to observe power distribution and verify essential systems.

• Why the other options complicate the test: they introduce unpredictable loads or disrupt the test environment.

• How to perform the check in a crew-friendly way: confirm sources, verify bus energization, scan for faults, observe stability, document results.

• How this step connects to CQ and KV expectations: it builds a reliable foundation for more nuanced checks and demonstrates disciplined electrical understanding.

If you’re navigating CQ and KV scenarios, that steady AC baseline is your friend. It keeps the data clean, the decisions sane, and the team aligned. And yes, it’s one of those small-but-crucial choices that prove you’re ready to handle the airplane as a cohesive, capable system rather than a collection of separate parts. So next time you’re in the cockpit and the question comes up, remember the steadiness of the AC supply—the anchor that helps you read the airplane the right way.