# Alerting Systems General Principles: Warning, Caution, and Advisory Logic

> Study alerting-system fundamentals under CS-25, including warning hierarchy, color coding, and cockpit master-warning/master-caution design principles.

- **Subject:** 022 — Instrumentation
- **Section:** 022-12 — Alerting Systems, Proximity Systems
- **Topic code:** 022-12-01
- **Last reviewed:** 2026-04-01
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/instrumentation/alerting-systems-proximity-systems/general/

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## Overview

The **Flight Warning System (FWS)** ensures the flight crew is aware of abnormal aircraft conditions. Its primary functions are to:
1.  **Draw attention** to the condition (Aural/Visual).
2.  **Identify** the specific problem.
3.  **Prioritize** alerts based on urgency (Internal Logic).

## Alert Categories (CS-25)

Alerts are categorized by the level of crew awareness and action required. The color coding is strictly regulated.

| Category | Color | Definition | Crew Action |
| :--- | :--- | :--- | :--- |
| **Warning** | **Red** | Emergency condition requiring **immediate** recognition and **corrective** action. | **Immediate** |
| **Caution** | **Amber / Yellow** | Abnormal condition requiring **immediate awareness** and **subsequent** corrective action. | **Subsequent** |
| **Advisory** | Any (Prohibited: Red/Green) | Condition requiring crew **awareness**. | **May be required** |

### Safe Operation
*   **Green** is reserved for indicating safe, normal operation (e.g., Landing Gear Down & Locked). It is **not** used for alerts.

## Location & Visibility

**Master Warning** and **Master Caution** lights must be installed in the pilot's direct **line of vision** (forward field of view) to ensure they are seen with minimum deviation from the normal flight path monitoring.

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Free study notes from pilotsyllabus.com. Not a substitute for training at an approved ATO.