GPS Spoofing vs. Jamming: A Pilot’s Guide to Part-IS Threats

In modern conflict zones, from Eastern Europe to the Middle East, the reliability of Global Navigation Satellite Systems (GNSS) is no longer guaranteed. GPS Spoofing and Jamming are the new threats in town, and understanding them is critical.

For decades, pilots have trusted the magenta line. But Regulation (EU) 2023/203 (Part-IS) forces us to re-evaluate that trust. Under IS.OR.205, operators must now identify and manage “Threat Scenarios” that endanger flight safety.

The most critical of these threats for Flight Operations is the distinction between Jamming and Spoofing. One is a nuisance; the other is a trap.

Here is the operational difference every pilot needs to know to maintain Part-IS compliance.

1. Jamming: The “Noise” (Loss of Availability)

Jamming occurs when a powerful transmitter on the ground blasts noise on the GNSS frequencies (L1/L5).

• The Effect: It overpowers the weak satellite signal. Your aircraft simply loses the ability to calculate a position.
• The Cockpit Indication: You get a “GPS LOST” or “NAV ACCURACY DOWNGRADE” message. The system fails safely and tells you it has failed.
• Part-IS Context: In the CIA Triad (Confidentiality, Integrity, Availability), Jamming is a loss of Availability. The data is gone, but it isn’t lying to you.

2. GPS Spoofing: The “Lie” (Loss of Integrity)

Spoofing is far more dangerous. It involves a sophisticated ground station transmitting a fake GPS signal that mimics a real satellite but carries false timing and position data.

• The Effect: Your aircraft thinks it has a solid lock. The autopilot follows the signal, but the signal is slowly drifting you off course—sometimes by miles.
• The Cockpit Indication: There may be no warning flag. You might see a “Map Shift” (where the digital map disagrees with the radar terrain) or a sudden, false “PULL UP” Terrain Warning because the aircraft thinks it is at ground level.
• Part-IS Context: This is a loss of Integrity. The system is technically “working,” but the data is false. As we teach in Course 1, integrity attacks are the highest risk to flight safety because they induce Automation Bias.

3. How to Recognize a GPS Spoofing Event

Under IS.OR.220 (Detection), pilots must be able to detect “anomalies”. Since the aircraft might not flag a spoofing event, you must look for the “Golden Rule” of cyber detection: Illogical Behavior.

• The Clock Check: GNSS is based on time. If your FMS clock suddenly jumps or changes time zones unexpectedly, suspect spoofing.
• The Map Shift: If your synthetic vision shows a mountain, but your eyes see a flat plain, trust your eyes.
• Contradictory Data: If the Captain’s ND shows one position and the First Officer’s ND shows another, you are likely under attack.

4. The Recovery Procedure (IS.OR.220)

If you suspect spoofing, Part-IS requires immediate “Containment”.

1. Disconnect: Do not let the FMS update its position from the corrupt GNSS source. Deselect GPS from the sensor logic if possible.
2. Revert to Raw Data: This is the ultimate fallback. VOR/DME and ILS signals are ground-based and much harder to spoof than satellite signals.
3. Report: Use the internal reporting scheme (IS.OR.215) to flag the zone for other crews.

Conclusion: Training for the Threat

The days of assuming the GPS is always right are over. IS.OR.240 requires that all flight crew are competent in recognizing these specific cyber-kinetic threats.

Raven’s EASA Part-IS Awareness Training prepares your personnel the modern threat landscape including GPS spoofing.