Understanding Ground Proximity Warning Systems (GPWS)

Introduction

Controlled Flight Into Terrain (CFIT) accidents have historically been among the deadliest in aviation. To combat this, aircraft are equipped with Ground Proximity Warning Systems (GPWS) that alert pilots if their aircraft is in immediate danger of crashing into the ground. This system is a vital topic covered extensively in DGCA Ground Classes.

1. What is GPWS?

GPWS is an onboard safety system designed to prevent unintentional collisions with terrain, especially during approach and landing. It uses data from:

• Radio altimeters

• Barometric altitude

• Aircraft configuration (gear/flap position)

• Speed and descent rate

When dangerous descent patterns or terrain proximity are detected, the system generates aural and visual alerts.

DGCA Ground Classes explain these systems with real-life accident case studies and simulator examples.

2. Alerts and Warnings Provided by GPWS

Typical GPWS warnings include:

• “Sink rate” – when the aircraft is descending too fast

• “Pull up” – when terrain collision is imminent

• “Too low, gear” / “Too low, flaps” – configuration warnings

• “Terrain, terrain” – terrain awareness alert

Students in DGCA Ground Classes are trained on how to react to these warnings within seconds, as every moment counts.

3. Enhanced GPWS (EGPWS)

Modern aircraft use Enhanced GPWS, which integrates GPS and terrain databases to provide predictive terrain warnings. Benefits include:

• Terrain mapping for areas beyond the aircraft’s current radar

• Look-ahead capability for mountain ranges or rising terrain

• Visual display of terrain on cockpit screens

EGPWS has become the industry standard and is a focus area in advanced systems training during DGCA Ground Classes.

4. Limitations and Human Factors

Although GPWS significantly improves safety, it can be limited by:

• Lack of terrain data in remote regions

• Delayed reaction in high-speed descents

• Pilot misinterpretation of alerts

That’s why pilot judgment, training, and prompt response are critical, and these are emphasized in DGCA Ground Classes.

Conclusion

GPWS is a life-saving technology that bridges the gap between automation and pilot awareness. Its proper use has saved countless lives in aviation.

Learn how to master terrain avoidance and safety procedures with expert instruction at DGCA Ground Classes and become a safety-first pilot.