Northrop Grumman, working closely with Raytheon Co., has reached three milestones in a program to modernize the B-2 stealth bomber’s radar system with an advanced, more reliable antenna. These achievements represent significant progress towards initial flight testing of the radar. Recently, the B-2 radar-modernization team passed a final design review by the US Air Force, delivered the first test model of the radar for integration, test and software development, and completed a suite of tests that proves the hardware and software work together as one subsystem. Northrop Grumman, prime contractor for the overall B-2 program, also leads the radar-modernization team that includes Raytheon, the radar system provider. This effort will replace the current antenna with an active, electronically scanned array (AESA) antenna. The final design review concluded in late May with the Air Force finding the radar system’s design in compliance with engineering and performance requirements. In July, Raytheon delivered on schedule the first model of its APQ-181 radar. The APQ-181 is one of a series of revolutionary AESA radar systems that are replacing mechanically scanned antennas with faster and more reliable solid-state arrays. Following the radar delivery, the B-2 team completed initial radar-subsystem integration and acceptance testing ahead of schedule, paving the way for higher level systems integration and performance tuning. The current B-2 radar work is part of a $383 M system development and demonstration (SDD) contract awarded by the Air Force in 2004. During the SSD phase, Northrop Grumman and Raytheon are developing and testing the radar and will install six systems on operational B-2 aircraft of the 509th Bomb Wing at Whiteman Air Force Base, MO. This phase will be followed by production to field the new radar and install the new antenna into the B-2 fleet.