French trio to deliver inertial navigation system for French Navy’s Mistral-class carriers

November 24, 2025, by Fatima Bahtić

French companies CNN MCO, Thales, and CS GROUP have entered into a strategic partnership to equip the French Navy’s amphibious helicopter carriers (AHCs) with a new, highly resilient inertial navigation system designed for electronic warfare environments.

The French Navy’s Fleet Support Service (SSF) is leading the program to modernize the navigation systems on its PHA-class amphibious helicopter carriers and has assigned the upgrade work to CNN MCO, the fleet support contract holder.

Awarded in 2022 for an eight-year period, this contract covers the maintenance and support of all onboard systems on the three PHA vessels, Mistral, Tonnerre, and Dixmude, as well as the in-service support of Somme, a BCR-type command and replenishment ship.

The overarching goal is to ensure high availability at sea and maintain the full operational capability of these platforms in an increasingly demanding and complex strategic environment.

The contract includes more than 40 modernization studies. Conducted across three separate vessels, these studies have already resulted in 50 upgrades in the last two years. CNN MCO is managing these phases in close coordination with the SSF, from preliminary design studies through to shipboard integration.

The Thales inertial navigation system TopAxyz will be integrated into CS Group’s global navigation system. The system relies solely on internally controlled data with no dependence on external sources. Using shipboard sensors such as accelerometers and gyroscopes, TopAxyz measures the vessel’s movements to continuously calculate its position, speed and heading, without the need for external signals such as GPS.

Installation of these navigation systems and related equipment is aligned with the SSF’s vessel maintenance schedule through to 2027. Mistral will be the first to benefit from the new system, followed by the Dixmude and Tonnerre. Once the Thales inertial units have been integrated into the navigation modules by CS Group, the systems will be installed by CNN MCO across the three vessels, with a progressive ramp-up aligned with this timeline.

CNN MCO is responsible for integration, test supervision, and equipment maintenance, working directly with the SSF teams. The aim is to optimize installation windows in order to ensure the operational availability of the systems at sea.

“This programme confirms CNN MCO’s ability to carry out complex upgrades in shipboard environments. We’re proud to contribute to the modernisation of sensitive equipment on these vessels as part of an all-French initiative, working with the SSF, Thales and CS Group,” Céline Barazer, Deputy Director of CNN MCO, an Equans France company, said.

“With 40 years of experience in inertial navigation systems for aircraft, space launchers, air defence systems and artillery, Thales is now bringing this know-how to naval operations. We’re proud to play a part in providing resilient navigation solutions for France’s naval vessels as a prerequisite for ensuring freedom of action by armed forces at sea,” stated Florent Chauvancy, Vice-President, Flight Avionics, Thales.

“A long-standing partner of the naval forces, CS GROUP is proud to support the fleet’s performance and safety, and to ensure the coherent and resilient integration of the entire navigation chain,” Frédéric Dussart, Director, Defence & Security Activities, CS Group, commented.