- U.S. Air Force plans a sole-source contract with Northrop Grumman to support F-35 AN/APG-81 radar and AN/AAQ-37 DAS software and sustainment capabilities.
- Move seeks to establish internal engineering control over F-35 sensor systems amid delays affecting integration of the next-generation APG-85 radar.
A newly published presolicitation notice shows the United States Air Force is preparing to award a sole-source contract to Northrop Grumman for support of the F-35 Joint Strike Fighter’s AN/APG-81 radar and AN/AAQ-37 Distributed Aperture System.
The notice, issued on March 19, 2026, outlines plans to expand software engineering and sustainment capabilities tied to the aircraft’s core sensor systems, with responses due by April 3.
According to the notice, the contract will cover program management, engineering services, and execution of data access and licensing agreements required to sustain and modernize the F-35’s radar and Distributed Aperture System software. The requirement also includes configuration management, transition planning, and the establishment of testing capabilities at Robins Air Force Base.
The Air Force Sustainment Center said the contractor will be required to provide access to source code, technical data, and software development environments, as well as support for integrating those tools into government-controlled infrastructure. These elements are considered essential to enabling long-term sustainment and updates to the aircraft’s mission systems.
The Air Force stated that the necessary technical data, tools, and expertise are proprietary to Northrop Grumman, making it the only viable provider for this work. Foreign participation is not permitted under the terms of the solicitation.
The AN/APG-81 radar is the F-35’s primary active electronically scanned array (AESA) sensor, designed to provide air-to-air and air-to-ground targeting, tracking, and situational awareness. The AN/AAQ-37 Distributed Aperture System complements the radar by using multiple infrared sensors positioned around the aircraft to provide full spherical coverage, enabling missile warning, tracking, and pilot vision support.
Together, these systems form a core part of the F-35’s sensor fusion architecture, allowing the aircraft to collect, process, and present battlefield data in a unified format for the pilot. Maintaining and updating the software that governs these systems is critical to ensuring the aircraft remains operationally relevant.
The Air Force’s decision to expand internal sustainment capabilities comes at a time when the F-35 program is facing reported challenges related to radar upgrades. Breaking Defense reported that, starting this fall, new F-35 aircraft delivered to the American military may be provided without installed radars due to delays with a next-generation system known as the APG-85.
According to that reporting, the APG-85 radar differs in size from the current APG-81, requiring structural changes in the aircraft. Because of those changes, the existing APG-81 cannot be installed in airframes configured for the newer radar. As a result, some aircraft could be delivered without a radar installed, limiting their operational use.
Sources cited by Breaking Defense said that aircraft delivered without a radar would remain airworthy but would not be combat-capable. “They can still take delivery of the jet. They can still use it as a flyable asset, [but] obviously not a combat-coded asset. So they can still do limited training with it,” one source said.
In the most constrained scenario described in the report, more than 100 aircraft could be affected if delays persist, though a shorter delay could limit the impact to a smaller number of jets. The issue centers on the timing mismatch between production of aircraft in Lot 17 and the availability of the new radar system.
Against this backdrop, the Air Force’s push to secure deeper access to software, data, and engineering tools for the existing radar and sensor suite reflects an effort to maintain continuity in capability and reduce reliance on external support for mission-critical systems.
Operationally, the AN/APG-81 radar and AN/AAQ-37 DAS are central to the F-35’s ability to detect threats, track targets, and operate in contested environments. The radar enables precision targeting and long-range detection, while the DAS provides persistent infrared coverage and missile warning, enhancing survivability and situational awareness.