First production unit of LN-351 system signals shift toward GPS-resilient operations
FALLS CHURCH, VIRGINIA — Northrop Grumman has delivered the first production unit of its next-generation Embedded GPS/Inertial Navigation System Modernization (EGI-M), marking a key milestone in the Pentagon’s push to ensure reliable navigation in contested environments.
The system, designated LN-351, will be deployed initially on the Lockheed Martin F-22 Raptor and the Northrop Grumman E-2D Advanced Hawkeye, two critical platforms for U.S. air superiority and surveillance. The upgrade is designed to allow both aircraft to operate effectively in environments where GPS signals are degraded, jammed, or entirely denied.
The delivery represents the transition of the program from development into operational fielding, following years of testing and validation.
M-code technology underpins enhanced resilience
At the core of the LN-351 system is its use of M-code, an encrypted military GPS signal broadcast by the latest GPS III satellites. Unlike standard GPS signals, M-code is significantly more resistant to jamming and spoofing, offering improved security and reliability for military operations.
The system also uses high-gain directional antennas to further strengthen signal integrity. In addition to navigation, the technology supports blue force tracking, allowing U.S. military aircraft to maintain awareness of friendly positions even in heavily contested airspace.
Under current Department of Defense requirements, all military GPS equipment acquired after fiscal year 2017 must be M-code capable, making systems like LN-351 central to modernization efforts.
Development timeline and testing milestones
The EGI-M program has been in development for several years. Northrop Grumman began engineering and manufacturing development in 2018 and completed its critical design review in 2020.
Testing has progressed steadily. In May 2023, the system successfully completed flight tests aboard a Cessna Citation 560 aircraft. More recently, in February 2025, the Air Force Life Cycle Management Center conducted six performance evaluation flights covering three EGI-M variants.
Lt. Col. Christopher Grover, the PNT program office materiel leader at the Air Force Life Cycle Management Center, stated that the new receiver gives U.S. military assets the ability to operate wherever needed, with full capability and on their own timeline.
Ryan Arrington, Northrop Grumman’s vice president for navigation and cockpit systems, added that EGI-M enhances operational effectiveness while offering the flexibility to counter current threats and adapt to future mission requirements, Air and Space Forces flagged.
Modular design and expanded capabilities
Beyond its jam-resistant GPS functionality, the LN-351 introduces several new capabilities aimed at future-proofing military navigation systems.
The system features a flexible software architecture capable of hosting third-party position, navigation, and timing (PNT) applications. This enables integration with additional sensors and even non-GPS satellite signals, improving accuracy and resilience.
Its modular hardware design allows it to integrate with existing aircraft navigation infrastructure, reducing installation complexity and enabling upgrades without requiring a full system replacement. The system has also completed all required technical and performance testing, clearing it for full-rate production.
Broader adoption expected across U.S. military platforms
While initial deployment will focus on the F-22 and E-2D, Northrop Grumman has identified several additional platforms as candidates for the LN-351 upgrade. These include the Northrop Grumman RQ-4 Global Hawk and Northrop Grumman MQ-4C Triton unmanned aircraft, the Boeing P-8 Poseidon, and the Sikorsky CH-53K King Stallion.
The potential integration across both fixed-wing and rotary platforms underscores the system’s flexibility and the growing importance of resilient navigation in modern warfare.
The effort is backed by a long-term contract awarded in 2019, valued at up to $1.39 billion over 13 years. The agreement covers production and sustainment of next-generation navigation systems for U.S. Air Force platforms as well as foreign military sales customers.
Strategic implications for contested environments
The fielding of LN-351 comes as U.S. defense planners increasingly prioritize operations in GPS-contested environments, where adversaries are investing heavily in electronic warfare capabilities.
By enabling aircraft to maintain accurate navigation and timing without reliance on vulnerable signals, the system is expected to play a critical role in maintaining operational effectiveness in future conflicts.
With the first production unit now delivered, Northrop Grumman’s EGI-M program moves into its next phase, bringing advanced, jam-resistant navigation capabilities closer to widespread deployment across the U.S. military.
