The US Air Force has launched a competition to replace its fleet of Northrop Grumman E-8C Joint Surveillance Target Attack Radar System (Jstars) tank hunters. The request for proposals (RFP) issued on December 28 is valued at $6.9 billion for development and production. The Air Force wants 17 radar-carrying battlefield surveillance, battle management and command-and-control aircraft, with initial operational capability preferably sooner than fiscal 2024. Northrop Grumman, Lockheed Martin and Boeing are already in the running, but surprise bids from companies such as Sierra Nevada Corp. are also possible.