Indicating and Recording Systems: Monitoring and Logging

Every flight depends on accurate information—from the moment you start engines until you shut down at the gate. But how does the A320/A321 transform raw sensor data into the clear, organized displays that guide your decisions? The indicating and recording systems solve this critical challenge by collecting, processing, and presenting flight information in a way that keeps you informed without overwhelming you. These systems ensure you always have the right information at the right time, whether you're managing normal operations or responding to emergencies.

How the System Works

The indicating and recording systems operate like a sophisticated information network with three main components working together. Display Management Computers (DMCs) serve as the central processors, taking raw data from sensors and systems throughout the aircraft and converting it into the visual displays you see. Three identical DMCs provide redundancy—DMC 1 typically drives the captain's displays and upper ECAM (or both ECAM DUs on some aircraft types), DMC 2 handles the first officer's displays and lower ECAM (on some aircraft types), while DMC 3 stands ready as backup.

System Data Acquisition Concentrators (SDACs) act as data collectors, gathering information from aircraft systems and formatting it for the DMCs and Flight Warning Computers (FWCs). Meanwhile, the FWCs monitor critical parameters and generate the alerts, warnings, and synthetic voice callouts that demand your attention when needed.

This architecture means your displays show processed, prioritized information rather than raw data. When you see engine parameters on the upper ECAM, those values have been collected by SDACs, processed by DMCs, and presented in a format designed for quick interpretation during different flight phases.

Primary Flight Display: Your Flight Reference

The Primary Flight Display (PFD) serves as your primary flight reference, but it adapts to how you're flying. When you select HDG/VS mode on the Flight Control Unit (FCU), the display emphasizes attitude-based flying with traditional flight director bars. Switch to TRK/FPA mode, and the Flight Path Vector (FPV)—commonly called "the bird"—becomes your primary reference.

The bird shows where your aircraft is actually going, accounting for wind effects. Its horizontal position relative to the fixed aircraft symbol indicates track, while its vertical position shows flight path angle. This becomes invaluable during non-precision approaches when you can set the inbound track and descent angle on the FCU, then simply align the bird with the flight path director symbol for a stabilized approach.

However, understand the bird's limitations. It's calculated using inertial data and can show track deviations of up to ±2 ° during approach due to inertial errors. It also depends on static pressure data, making it unreliable if altitude information is compromised. The key technique: adjust attitude first, then confirm the result by referencing the bird.

Speed indications on the PFD provide multiple layers of protection. The amber strip shows your minimum selectable speed (VLS)—the lowest speed you can select while maintaining an adequate stall margin. The red strip indicates the maximum allowable speed (VMAX), determined by the most restrictive of VMO/MMO, VLE, or VFE. During approach, these visual cues help you maintain the speed envelope without constantly referencing numbers.

Navigation Display: Your Situational Awareness Tool

The Navigation Display (ND) transforms navigation data into visual situational awareness. In ROSE modes, your aircraft sits at the center with a compass rose showing magnetic heading, while ARC mode provides a forward-looking view ideal for weather avoidance and terrain awareness. PLAN mode lets you examine your entire flight plan without NAVAID clutter.

The flight plan appears as color-coded lines: active segments in green, missed approaches in blue, and temporary revisions in dotted yellow. Waypoint constraints display up to three lines of information—altitude, speed, and time restrictions that help you understand the flight plan's requirements at each point.

Understanding cross-track error helps you monitor navigation accuracy. When RNP is ≤ 0.3 NM, errors display with 0.01 NM precision between 0.02 and 0.29 NM, giving you precise feedback on your navigation performance. The system suppresses error display below 0.01 NM to avoid unnecessary clutter.

ECAM: Your System Monitor and Advisor

ECAM operates in four distinct modes, each serving a specific purpose. Normal mode automatically displays system pages relevant to your current flight phase—you’ll see the WHEEL page during taxi, the ENGINE page during start, and the CRUISE page at altitude. Failure mode immediately presents emergency procedures with associated system synoptics when problems occur.

Advisory mode alerts you when parameters drift outside normal ranges—the affected value pulses while the relevant system page appears automatically. Manual mode lets you call up any system page using the ECAM control panel, though failures and advisories will override your selection.

The Engine/Warning Display (E/WD) prioritizes information presentation. Primary failures appear as boxed titles, secondary failures show with asterisks, and action lines automatically clear as you complete required actions. During high-workload phases like takeoff and landing, inhibition logic prevents non-critical alerts from distracting you—you’ll see "T.O. INHIBIT" or "LDG INHIBIT" memos in magenta during these phases.

Managing Information Flow

The system includes sophisticated logic to prevent information overload. Flight phase inhibition delays non-critical warnings during critical phases—a failure occurring during taxi might not be displayed until after takeoff, when you have the capacity to address it. The STATUS page consolidates operational information, including speed limitations, approach procedures, and cancelled cautions, in organized sections.

ECAM control functions give you management tools: the CLR button clears completed actions and scrolls through overflow messages, RCL recalls previously cleared alerts, and EMER CANC silences aural warnings while keeping visual alerts active. Understanding these controls helps you manage information flow during complex situations.

Recording and Documentation

Behind the scenes, the Flight Data Recording System continuously captures your flight for analysis and safety purposes. The system includes crashproof units combining voice, data, and datalink recording with underwater locator beacons. Recording activates automatically—on the ground during the first 5 min after electrical power-up and whenever engines are running, then operates continuously in flight.

The Aircraft Integrated Data System (AIDS) tracks system parameters for maintenance insights, generating both automatic reports and custom reports accessible through the MCDU. This data helps maintenance teams understand system performance trends and plan preventive actions.

What This Means for You

Understanding the indicating and recording systems transforms you from a passive consumer of information to an active manager of your information environment. You'll recognize when displays show processed versus raw data, understand why certain alerts appear when they do, and know how to configure displays for maximum situational awareness.

During normal operations, trust the system's automatic presentation logic while knowing how to manually access information when needed. During abnormalities, understand that ECAM's prioritization and inhibition logic helps you focus on what matters most at each phase of flight. The bird becomes a powerful tool for precision flying when you understand its capabilities and limitations.

Most importantly, recognize that these systems don't just display information—they actively filter, prioritize, and present it to support your decision-making throughout every phase of flight. This understanding helps you work with the systems rather than simply reading from them, making you a more effective pilot of this sophisticated aircraft.

How the A320 turns raw sensor data into actionable cockpit information – PFD logic, ECAM modes, flight path vector, and what the displays tell you in failures.