Navigating the Threats of GPS Jamming and Spoofing

GPS Jamming and Spoofing: Effects on Piloting Operations

The maritime industry has undergone a transformation in recent years, becoming increasingly dependent on electronic systems and satellite-based navigation systems with the rapid integration of technology. However, this dependency has led to certain risk concepts in maritime jargon evolving from mere terms into tangible threats to daily operations. The concepts of jamming (signal interference) and spoofing (signal deception) have become threats that we hear more frequently, especially following the Russia-Ukraine War and regional conflicts in the Middle East and the Red Sea, and have even been experienced in the areas where we operate ships or provide pilotage services.

Since the introduction of satellite positioning systems on ships, there have been myths regarding the potential risks of these systems, such as the possibility of being turned off by the countries that own the satellites or providing incorrect position information. I am sure many of us have heard these topics since the systems were first implemented. During my student years, our late teacher Güven Tuncer, who taught us the intricacies of finding positions at sea and plotting positions on paper charts, shared a detail he noticed while reviewing the internship notebook of a student who had just returned from a long internship. The intern noted that although his ship was sailing in the Black Sea, the GPS device temporarily showed a position in a completely different region of the world and on land. While relaying this incident to us, our teacher pointed out that satellite systems could occasionally be tested in this manner by the countries that own them, advising us never to fully trust electronic devices and to master traditional methods. Thanks to the additional satellites (DGPS), the system provides real-time and continuous position information with a precision that has dropped to nearly one meter without requiring any manual calculations, offering a revolutionary convenience in maritime operations. This effortless high reliability, which eliminates the complex mathematical calculations of traditional methods and the risks of incorrect positioning due to human error, has made us forget throughout our maritime lives the possibility that GPS systems could be manipulated or lead to major accidents.

In this article, I will examine the concepts of jamming and spoofing not just in a theoretical framework but also in terms of their operational reflections on the bridge, recent maritime accidents, and particularly their effects on pilotage services.

Concepts of GPS Jamming and Spoofing

GNSS, or Global Navigation Satellite Systems (GPS, Galileo, GLONASS, etc.), send low-power radio signals from satellites in orbit to ships or receiving stations. Since GPS is the most widely known and used system in the industry, interventions related to these systems will be defined in the maritime industry as GPS throughout the remainder of the article. The weak nature of the signals coming from GPS satellites makes them extremely vulnerable to malicious interventions from outside. These interventions are generally divided into two main categories: signal jamming and signal spoofing.

Signal Jamming: This is the act of preventing receivers in the targeted area from detecting satellite signals by broadcasting a much higher and stronger artificial noise, or frequency, within the frequency range in which global navigation satellite systems operate. As a result, the system becomes locked, and during the exposure period, position information cannot be obtained from the satellites, leading to immediate audible and visual alarms from the navigation devices on the ship's bridge.

Signal Spoofing: Spoofing is a much more complex type of cyber attack than jamming, where false data that mimics satellite signals is produced to deceive the ship's GPS receiver. The device does not realize that there is a malfunction and believes it is operating normally. However, the ship's calculated position, speed, and course have been secretly manipulated.

Although the concepts of jamming and spoofing are very similar, the fundamental differences between them can be summarized in the table below:

| Jamming (Signal Interference) | Spoofing (Signal Deception) |

|--------------------------------|------------------------------|

| **Operating Mechanism** | Suppressing satellite signals with high frequency |

| | Misleading and manipulating the satellite receiver with false signals |

| **System Response** | Signal loss and interruption, GPS screens freezing |

| | The system appears normal, but the position information is incorrect |

| **Bridge Effect** | Instantaneous and multiple alarms on navigation devices |

| | No alarms, and devices show false position information |

| **Detectability** | Easy for personnel to detect with alarm sounds |

| | Requires visual verification and checks to be noticed |

General Risks and Effects on Navigation Safety

The loss or manipulation of GPS data on a ship does not merely mean that the position on the map is erased. Bridge systems such as ECDIS, AIS, and autopilot operate directly with GPS data. Particularly, since AIS devices receive dynamic data such as the position, speed, and course of targets directly from satellite systems, in the event of regional jamming, surrounding ships also become unable to broadcast their positions. As a result, the ship becomes somewhat blind, AIS targets on the screens disappear, and there is significant alarm chaos on the bridge.

A much more insidious and critical risk than the complete signal loss scenario is the cases of spoofing, where data is secretly manipulated. While the ship is actually heading towards a shallow area, the ECDIS screen may show that it is navigating in safe waters. These risks are not merely theoretical possibilities; they are realities confirmed by painful experiences in the recent past. For example, in June 2025, near the Strait of Hormuz, reports of intense GPS spoofing activities were documented in the collision accident between the VLCC 'Front Eagle' and the Suezmax 'Adalynn' tankers, and it was observed that the AIS route traces of the ships passed over land masses. This incident, which occurred among ships carrying hazardous cargo, is considered one of the most concrete examples of how manipulated position information can lead directly to physical collisions. The severe fire and environmental pollution that occurred after the collision is also the clearest evidence of how a small manipulation of position on digital screens at sea can have devastating consequences.

In such a signal manipulation, the position information broadcasted via the ship's AIS device will be incorrect, leading to the transmission of false AIS position information to surrounding ships or authorities such as Vessel Traffic Services. If AIS data is used on ARPA radar, ghost ship routes will emerge. One of the most dangerous points is that due to the normalization of such interventions in certain regions because of ongoing global wars, the ship's crew may lose awareness of this issue. Over time, the crew becomes desensitized to the constantly ringing malfunction alarms, which can lead to overlooking potential real dangers and vital threats that are not GPS-related. Additionally, the simultaneous presentation of conflicting data from multiple devices will increase the cognitive load on the bridge team, hindering their ability to make correct decisions during a crisis.

Effects on Piloting Operations and Ship Maneuvers

A GPS failure occurring in open waters can be tolerated using alternative traditional navigation methods (such as celestial navigation or dead reckoning). However, in waters where ships are approaching ports, navigating narrow channels, and encountering navigation hazards with heavy traffic, the margin for error will be quite low.

Port areas and narrow channels are inherently restricted areas where ships pass very close to each other and depths fall below limits. Even during these routine maneuvers, there is already significant alarm traffic on the bridge due to warnings such as CPA (Closest Point of Approach), shallow water, or course deviation. Indeed, the International Maritime Pilots' Association (IMPA) has recently raised the issue of how alarm chaos and unnecessary noise on the bridge during piloting operations distract pilot captains through a special survey it conducted. When the results of this survey conducted by IMPA are officially announced, I plan to analyze the obtained data and the effects of alarm fatigue on maneuver safety in detail in a future article. However, one clear fact at this stage is that adding false and continuous alerts caused by GPS spoofing or jamming to this routine alarm situation, which already significantly increases the cognitive load on the bridge team, can complicate the decision-making mechanism of the pilot captain managing the maneuver during a crisis in narrow waters.

The Turkish Pilots' Association (TKKD) also draws attention to this vital issue facing the maritime industry in its announcement titled 'Request for Information on GNSS Spoofing and Jamming Events' published on March 10, 2026. In this announcement, it was stated that as part of a large-scale study conducted by the European Maritime Pilots' Association (EMPA), pilot captains working in Turkey are requested to document the real intervention cases they encounter in the field to be used in analyzing risks to maritime safety at the international level and in creating new regulations. Indeed, in March 2025, EMPA, along with the European Tugowners Association (ETA) and the European Dredging Association (EuDA), emphasized the seriousness of this threat in a joint statement submitted to the European Commission. The statement clearly expressed that the presence of highly trained professionals, such as pilot captains who will take the initiative to safely manage the ship during unpredictable crisis moments when digital autonomous systems are misled or manipulated, is of vital importance.

When evaluating the navigation areas subject to piloting operations, it is particularly noteworthy that in long channel navigation in certain countries, portable pilot units (PPUs) brought by pilot captains serve as important decision support systems, providing high-precision navigation data such as position, speed, and rate of turn (ROT) largely through independent satellite sensors and Real-Time Kinematic (RTK) corrections. However, a professional spoofing attack that could occur during the use of these devices could manipulate the data provided by the PPU, leading to irreparable accidents. The intervention may not only involve a static position shift but also aim to disrupt the pilot captain's perception of the ship's momentum through small interventions on speed vectors and rate of turn (ROT). The reflection of these theoretical risks in the field is quite striking. Particularly due to the increasing cases of electronic manipulation in Northern Europe, institutions such as the Norwegian Coastal Administration (NCA) are issuing serious warnings regarding navigation safety. Reports from the field and feedback from pilot captains indicate that GPS signal loss or interference is being experienced with increasing frequency in both ship equipment and PPU devices. Due to this high risk, many European countries, including the Netherlands Pilotage Organization (Loodswezen), have decided to equip PPU devices with special jamming and spoofing warning systems. Additionally, the integration of Inertial Measurement Units (IMUs/INS) into next-generation PPU hardware has been an important technological step toward providing the critical few minutes of accurate inertial data needed to safely cancel maneuvers, even if GPS signals are lost or manipulated.

One of the most recent and striking examples of the operational consequences of GPS interventions occurred on May 11, 2025, in the Red Sea. The container ship MSC ANTONIA, with a capacity of 7,000 TEU, ran aground approximately 100 nautical miles south of Jeddah. Just two days before the accident, a warning of intense GPS signal jamming was reported in the area by UKMTO, and the inconsistent and irregular route traces in the ship's AIS records revealed that the accident was directly caused by GPS manipulation. Even the tugboats that came to assist in the area were exposed to similar signal anomalies, severely complicating the coordination and position verification processes between the main ship and the rescue elements. This incident serves as an example of a risk that threatens the safety of pilotage in port approaches, once again highlighting the vital importance of signal security in routes requiring high-precision positioning.

As all these incidents demonstrate, especially the mismatch between radar images and ECDIS data in a narrow channel creates a dangerous contradiction between the visual perception obtained by the pilot captain looking outside and the instrumental data.

Regarding tug operations, another critical component of ship maneuvering; there have not yet been any reported direct accident effects of jamming and spoofing cases in the literature. Although tugs may be exposed to these signal manipulations, their high maneuverability, geographical familiarity in narrow waters, and the nature of the operation often allow them to use visual navigation methods to eliminate these risks. Furthermore, the difference between the frequency band in which the GPS system operates and the VHF radio frequency bands, which are the primary communication means between the pilot captain and the tug, also allows for the continuation of communication safety in cases of spoofing or jamming.

Management of Risks and Return to Traditional Positioning Methods

To successfully manage the risks associated with GPS, it is crucial to verify positions using alternative methods suitable for the dynamics of the navigation area, fostering awareness and a state of suspicion. The positioning methods to be applied to ensure navigation safety can be categorized based on the ship's location. In areas such as coastal navigation and narrow waters, where land masses can be used for triangulation; traditional methods such as adding radar images to ECDIS screen displays (radar overlay), confirming the ship's position using parallel indexes, and taking visual bearings should be given absolute priority, independent of GPS data. Additionally, cross-checking the depths read from the depth sounder with the contours on the ECDIS map will be another critical step in detecting manipulation. On the other hand, in open sea navigation where no land masses can be used for triangulation; checking approximate positions using gyro compass and dead reckoning techniques, as well as applying traditional celestial navigation practices, will be alternatives to ensure navigation safety during the dark moments left by GPS.

While celestial navigation is the only alternative to electronic navigation in open sea navigation, the lengthy calculation processes and practical challenges it poses can be a barrier for today's mariners. At this point, innovative solutions that blend technology with traditional methods come into play. Indeed, one of the recent developments that inspired me in preparing this article was the professional exchange of information I had with South Korean Dr. Young Sub Lee through LinkedIn. The digital sextant developed by Dr. Lee and his team, which has already been integrated into the standard navigation equipment of the South Korean Navy, can perform independent position calculations in less than a second by combining traditional celestial navigation principles with modern algorithms. Dr. Lee states that the aim of his innovative approach is not to completely replace existing electronic navigation systems but to provide ships with a quick and reliable positioning reference during crisis moments when GPS signals are jammed or manipulated.

Beyond all these operational and technical risks, another point that should not be forgotten is how the legal liability of the ship's captain and the pilot captain will be evaluated in terms of maritime law in the event of an accident caused by manipulated data due to cyber interventions, which will also be a separate topic of discussion.

At this point, pilot captains are evolving from being local information providers in digitizing ship bridges to becoming ultimate cyber-physical verifiers who confirm the truth through visual and experiential methods during crisis moments when electronic systems are manipulated.

Dr. Capt. Mustafa SÖKÜKCÜ

[email protected]

Sources Utilized:

Turkish Pilots' Association (TKKD). 'Request for Information on GNSS Spoofing and Jamming Events,' announcement dated March 10, 2026.

Riviera Maritime. European tug owners and pilots: safety is paramount for EU port strategy. https://www.rivieramm.com/news-content-hub/news-content-hub/european-tug-owners-and-pilots-safety-is-most-important-for-port-strategy-84300

Lee, Y. S. Korea digital sextant: LEEYOUNG SND_DS_Ev2.0 (Technical Presentation / Company Brochure).

Maritime Global Security (2nd Edition). Jamming and Spoofing of Global Navigation Satellite Systems (GNSS). https://www.maritimeglobalsecurity.org/media/2cwigtc4/2025-jamming-and-spoofing-2nd-ed-web.pdf

Riviera Maritime. MSC box ship grounds in apparent GPS jamming incident. https://www.rivieramm.com/news-content-hub/news-content-hub/msc-box-ship-grounds-in-apparent-gps-jamming-incident-84821

Cydome. Tankers collide in the Gulf, analysts suspect GPS jamming. https://www.cydome.com/blog/tankers-collide-in-the-gulf-analysts-suspect-gps-jamming

Splash247. MSC boxship grounds in the Red Sea amid GPS jamming reports. https://splash247.com/msc-boxship-grounds-in-the-red-sea-amid-gps-jamming-reports/

GEOD. How a PPU determines accurate position and speed. https://geodproducts.com/vessel-position-accuracy-pilots-need-ppu/

Schuttevaer. Rotterdam Port PPU Usage and Digital Navigation Reports. https://www.schuttevaer.nl/

Source: SeaNews Türkiye