Glass Cockpit Instruments & Partial-Panel Procedures for Charter Crews

Reading the PFD: Glass Cockpit Instruments & Partial-Panel Procedures for Charter Crews

Why Glass Cockpit Proficiency Is a Safety-Critical Skill for Charter Crews

The glass cockpit has redefined how crews process flight information — but it has not eliminated the need for partial-panel proficiency. The FAA's Q2 2026 Transport Airplane Issues List includes a dedicated avionics item on how non-primary flight and navigation information is displayed on the primary flight display, confirming that display content and information hierarchy remain active, unresolved certification concerns. Now imagine hand-flying an approach in instrument meteorological conditions when your PFD's attitude tape silently drifts five degrees — and the failure flag has not yet appeared.

In a modern EFIS-equipped flight deck, the PFD consolidates attitude, airspeed, altitude, vertical speed, and flight director/autopilot cues into one main reference. That consolidation is powerful — but it creates a single-point-of-reference dependency. When the display degrades, charter crews face a system management problem, not merely an instrument scan problem.

This article gives Part 135 and charter crews a practical framework for reading the PFD, recognizing failures, and flying safely under degraded conditions. The core argument is direct: managing a PFD failure requires a structured "recognize, verify, revert, fly" sequence, an understanding of standby instrument independence, and recurrent training built around realistic EFIS failure scenarios — not rote checklist memorization. Partial panel flying has changed form, but it has not disappeared.

What the Glass Cockpit PFD Actually Shows — and What Can Go Wrong

The PFD presents a layered information hierarchy. At its center is the attitude indicator — the synthetic horizon that replaces the traditional gyroscopic instrument. Flanking it are the airspeed tape on the left and the altitude tape on the right, each with trend vectors projecting where values are heading. Vertical speed is displayed adjacent to the altitude tape. Below the attitude display, the heading or track indicator provides directional reference, and overlaid on the attitude are flight director bars guiding the crew toward the commanded flight path.

Modern EFIS suites increasingly blend primary flight data with enhanced vision symbology and non-primary navigation information. FAA AC 20-167B, issued 2025-09-08, provides airworthiness approval guidance for Enhanced Vision Systems, Enhanced Flight Vision Systems, and Combined Vision Systems — all of which integrate with PFD displays. That "clean-looking" primary flight display is actually a composite of multiple data sources, processors, and software layers.

Failures in this architecture are not always total-display blackouts. Operational safety reports indicate that heading discrepancies on a single PFD during processor faults can become substantial before the system flags the failure. A crew expecting an obvious blank screen may miss a subtle, creeping error — and that is where the real danger lies.

Common PFD Failure Modes in EFIS-Equipped Aircraft

Charter crews should expect the following failure presentations, recognizing that avionics failure annunciation logic varies by manufacturer and aircraft type — a critical consideration for mixed-fleet operators:

Red X or amber flag on attitude, airspeed, or altitude — the most obvious indication that a data source has been declared invalid by the system.
AHRS miscompare annunciation — the attitude and heading reference system detects a disagreement between redundant sensors, alerting the crew to a data miscompare condition.
Single-source reversion without crew action — the system automatically switches to a backup data source, potentially without a prominent annunciation.
Partial data loss — some tapes remain valid while others do not, creating a mixed-reliability display that demands careful cross-checking.
Autopilot disconnect triggered by display validity loss — the automation rejects degraded data and hands control back to the crew, often at the worst possible moment.
Incorrect attitude or heading on one display — the most insidious failure, where data appears normal but is wrong, requiring crew cross-check to detect.

Glass Cockpit Partial Panel Procedures: The Four-Step Response

When the PFD fails in a glass cockpit aircraft, the answer is a structured decision sequence — not a moment of improvisation. Primary flight display failure management depends on executing four disciplined steps in order. Safety educators consistently make the same point: the easy part is seeing the red X or failure flag; the difficult part is knowing the aircraft-specific backup logic and the exact pilot response sequence.

Partial-panel competence in a glass cockpit is a system management skill. The pilot's workload shifts from "find the broken gauge" to "manage the failed system architecture." Crews must handle sensors, annunciators, display modes, and automation simultaneously — while continuing to fly the aircraft. Treat the autopilot as potentially untrustworthy the moment display validity is in question.

Step 1 — Recognize the Anomaly

Recognition includes both flagged failures — red X indications, amber flags, master caution alerts — and unflagged anomalies such as subtle attitude drift or heading creep. Cross-check between both PFDs and the standby instruments immediately. If something looks wrong, assume it may be wrong until confirmed otherwise. Do not wait for the system to tell you there is a problem.

Step 2 — Verify Which Data Sources Are Valid

Answer two questions immediately: What failed? What still has valid data? Compare captain-side and first-officer-side displays, check the standby instruments, and read every annunciator message. Sensor redundancy is your ally, but only if you actively interrogate it. A red X on one PFD identifies the bad source — it does not mean the problem is resolved. The crew must confirm which references are trustworthy and which are not.

Step 3 — Revert to the Safest Display Mode

Reversionary mode transfers valid data from one display unit to another, giving the crew a usable primary reference. The correct reversion depends on your aircraft type and EFIS suite. Some systems auto-revert; others require deliberate crew action. Know which type you are flying before you need it — this is not a procedure to discover during the emergency.

Step 4 — Fly the Aircraft

Disconnect the autopilot if its data sources are suspect. Transition to raw-data flying using known-good references. Automation modes can follow degraded data right into an unusual attitude, so an engaged autopilot is not a guarantee of safe control. Fly pitch and power, hold heading, and stabilize the aircraft before attempting to troubleshoot further. The aircraft does not care about your system diagnosis — it cares about angle of attack and flight path.

What do you do when the PFD fails in a glass cockpit aircraft?

When the primary flight display fails in a glass cockpit aircraft, execute the recognize-verify-revert-fly sequence: (1) recognize the failure — flagged or unflagged; (2) verify which data sources remain valid by cross-checking both PFDs and standby instruments; (3) revert to the appropriate reversionary display mode for your EFIS suite; and (4) fly the aircraft on raw data with automation disconnected if data integrity is in question.

Standby Instruments: Your Independent Lifeline in a Glass Cockpit

Understanding what your standby instruments in a glass cockpit aircraft actually provide — and where their power comes from — is essential before you need them. The misconception that standby attitude indicators are only for older airplanes is dangerous. In many modern aircraft, the standby attitude, airspeed, and altitude indicators provide an independent reference when the PFD or the entire EFIS architecture becomes unreliable. That independence is the entire point.

Charter crews must know three things about their standby systems:

Power source: Is the standby electrically powered or vacuum powered? Does it run on the aircraft's main bus, an emergency bus, or an internal battery?
Duration: How long does the backup last on its independent power source?
Source independence: Does the standby system share any failure path with the primary flight display? If the same AHRS feeds both the PFD and the standby, the "backup" may fail alongside the primary.

Understanding power-source independence is not academic — it determines whether the backup will actually be available during the failure that took the primary down. Verify this during preflight, not during the emergency.

Glass Cockpit vs. Steam Gauges: How Partial Panel Flying Has Changed

The short answer: detection is often easier in glass cockpit aircraft, but system management is more complex. In a traditional analog panel, a failed attitude indicator meant physically covering the instrument and redistributing your scan across the remaining gauges — airspeed, altimeter, turn coordinator, heading indicator. The failure was mechanical, and the response was mechanical.

In an EFIS-equipped aircraft, the system often flags the failure with a red X or amber annunciation. That is a genuine improvement. But the crew's task after detection is more involved: interpret software logic, evaluate annunciation messages, determine whether the system has auto-reverted or requires manual reversion, cross-check multiple electronic data sources, and decide whether automation should be trusted or disconnected. Partial panel in a glass cockpit is not simpler — it demands a different and often deeper kind of system knowledge.

The misconception that glass cockpits eliminate partial-panel flying persists in some training environments. The reality is that they change its form. Crews still face sensor failures, display degradation, and reversion decisions. The instrument scan technique for IFR in a glass cockpit must account for these realities.

Training That Builds Real Glass Cockpit Partial-Panel Competence

Recurrent training must build genuine system management proficiency — the ability to answer three questions instantly: What failed? What still has valid data? What is the safest reversionary mode? EASA CS-FSTD Issue 1, published in 2026, signals that regulators expect simulator-based training for partial panel and EFIS failure scenarios. Charter operators should treat this as a baseline expectation, not an aspirational goal.

Scenario-based modules are especially valuable for charter crews because their fleet mix can be broader than airline fleets. A crew flying a Phenom 300 on Monday and a Citation XLS on Wednesday faces two different EFIS suites with different failure annunciation logic and reversionary procedures. E-learning modules using animated cockpit scenarios can bridge this gap by showing how the same failure presents differently across aircraft types — complementing simulator sessions with accessible, repeatable study. Charter operators building or updating their Part 135 training programs can find structured curriculum options through CTS's Part 135 Training.

Essential Recurrent Training Scenarios for Charter Crews

The following scenarios should be part of every partial panel flying glass cockpit charter training program:

PFD attitude loss: Trains immediate recognition and transition to standby instruments — the foundational partial-panel skill in any EFIS aircraft.
Attitude indicator failure with autopilot disconnect: Combines instrument failure with sudden workload increase, testing hand-flying discipline under stress.
Heading miscompare / AHRS disagreement: Forces crews to evaluate competing data sources and determine which reference to trust.
Reversionary mode selection: Tests whether crews know the aircraft-specific procedure to transfer valid data to their display — a skill that cannot be generalized across fleet types.
Standby instrument scan and primary-reference transfer: Builds the scan pattern and display trust transition that replaces normal PFD reliance.
Manual flight under workload and distraction: Replicates the operational reality where failures coincide with ATC instructions, weather deviations, or approach briefings.

Regulatory Framework: What Charter Operators Must Know

Charter operators must understand the regulatory environment shaping glass cockpit partial panel procedures:

FAA 14 CFR Part 135 requires recurrent training and instrument proficiency checks for charter operators. While the regulation does not prescribe specific glass cockpit failure scenarios, proficiency in abnormal and emergency procedures — including instrument failure events — falls squarely within this mandate.
FAA AC 20-167B, issued 2025-09-08, provides airworthiness approval guidance for EVS, EFVS, and CVS equipment that integrates with PFD displays. This advisory circular reflects the increasing complexity of what appears on the EFIS primary reference.
FAA Q2 2026 Transport Airplane Issues List includes an active certification item addressing the display of non-primary flight and navigation information on PFDs — evidence that partial panel considerations extend to how information is presented, not just whether it is available.
EASA CS-FSTD Issue 1 (2026) establishes updated flight simulation training device requirements, supporting the use of high-fidelity simulators for EFIS failure and reversionary-mode training.
ICAO's competency-based training framework supports scenario-based training for abnormal instrument indications, cross-checking, and automation management — providing a global philosophy that reinforces national requirements.

Flying Safely When the Glass Cockpit Screen Goes Wrong

Managing a PFD failure in a glass cockpit is a system management discipline. It requires charter crews to master a structured sequence — recognize the anomaly, verify which data sources remain valid, revert to the safest display mode, and fly the aircraft — while simultaneously managing automation, annunciators, and cockpit resource management under pressure.

The goal is not to fear the technology. It is to understand it deeply enough to manage its failures with confidence. Every crew member should know the power source of the standby instruments, the reversionary logic of the EFIS suite they are flying, and the exact point at which automation should be disconnected. Partial panel competence in the modern flight deck is earned through structured, scenario-based training — not through hope that the screens will never fail.

Charter operators can build this competence into their Part 135 recurrent training programs by integrating e-learning modules and simulator scenarios that reflect the real failure modes their crews will face. The investment is not optional — it is a professional obligation.

Explore CTS's Part 135 training programs to build glass cockpit partial-panel proficiency into your charter operation's recurrent training curriculum.