A Mode S upgrade to the identification-friend-or-foe interrogator on Britain's Sentry E-3D aircraft has been performed by Northrop Grumman.

The upgrade for the IFF used on the Sentry, an airborne warning and control system aircraft, or AWACS, was the most complex series of modification it has performed for the Sentry fleet, it said.

"This innovative system upgrade has eliminated the need for complete mission computer replacement, thereby providing the Ministry of Defense with a comprehensive, affordable solution to the Civil Aviation Authority's upgrade requirement," said John Parker, director, weapon system sustainment and modernization, Northrop Grumman Technical Services. "The new, open architecture system also provides a foundation for future incremental hardware and software upgrades to support sustainment of the Sentry E-3D."

The IFF interrogator is an airborne defense system for long-range, rapid early warning and detection. It allows for discrimination between friendly and hostile aircraft. The Mode S system enables the Sentry to be operated in controlled airspace.

The work was performed under Northrop's existing Sentry E-3D Whole Life Support Program for Sentry aircraft, with BAE Systems and AAR as part of the company team.