HomeAbout UsFact SheetsDisplay

Ballistic Missile Early Warning System

Ballistic Missile Early Warning Radar

Ballistic Missile Early Warning Radar


The Air Force maintains three BMEWS Radars. These radars are capable of detecting ballistic missile attacks and conducting general space surveillance and satellite tracking. They are located at Thule Air Force Base, Greenland; Clear Air Force Base AK.; and Fylingdales Royal Air Force Station, England.

The BMEWS have two faces for a 240 degree coverage, Fylingdales is the exception with three faces for 360 degree coverage.  These sites were designed primarily to detect and track intercontinental Ballistic Missiles (ICBMs) and conducting general space surveillance and satellite tracking. Missile Warning and attack characterization data is sent to the United States' Missile Warning and Space Control Centers, the U.S. National Military Command Center and U.S. Strategic Command. Satellite tracking data is sent to the Joint Space Operations Center (JSpOC) for processing. 

Two of the BMEWS radars, Thule and Fylingdales have been modified to support the Missile Defense mission through the Upgraded Early Warning Radar (UEWR) program.  The UEWR upgrades modernized the hardware and software to improve midcourse BMDS sensor coverage by providing critical early warning, tracking, object classification, and cueing data.
All systems are operated by US and Canadian personnel with the exception of the Fylingdales system which is operated by the British Royal Air Force. The UEWR systems have a co-primary missions to provide missile tracking data to the U.S. Missile Defense Agency (MDA) GMD Fire Control Center (GFC/C) while simultaneously providing Missile Warning Data to the Integrated Tactical Warning and Attack Assessment (ITW/AA) system. Clear will be upgraded through the UEWR program with an estimated completion date in FY2018.


The unique aspect of the radars is their phased array antenna technology. The systems differ from mechanical radars, which must be physically aimed at an object for tracking and observation. The phased array antenna remains in a fixed position. Phased array antenna aiming, or beam steering, is done in millionths of a second by electronically controlling the timing, or phase, of the incoming and outgoing signals.

Controlling the phase through the many segments of the antenna system allows the beam to be rapidly projected in different directions. This allows interweaving of tracking pulses with surveillance pulses, allowing tracking of multiple targets while maintaining the surveillance responsibility.


A phased array antenna, as with any other directional antenna, will receive signals from space only in the direction in which the beam is aimed. The maximum practical deflection on either side of antenna center of the phased array beam is 60 degrees. This limits the coverage from a single antenna face to 120 degrees. To provide surveillance across the horizon, the building housing the entire system and supporting the antenna arrays is constructed in the shape of a triangle. The two building faces supporting the arrays, each covering 120 degrees, 240 degrees of azimuth. The array faces are also tilted back 20 degrees to allow for an elevation deflection from three to 85 degrees above horizontal.

The radar system is capable of detecting and tracking multiple targets that would be indicative of a massive missile attack. The system must rapidly discriminate between vehicle types, calculate their launch and impact points, and perform scheduling, data processing and communications requirements. The operation is semi-automatic and requires highly trained personnel for monitoring, maintenance, prioritization, scheduling, and as a final check of the validity of warnings. Four different computers communicate with each other from the heart of the system, which relays the information to Cheyenne Mountain Air Force Station and missile defense forward users.

Point of Contact: Air Force Space Command, Public Affairs Office; 150 Vandenberg St., Suite 1105; Peterson AFB, Colo., 80914-4500; DSN 692-3731, or (719) 554-3731; Fax (719) 554-6013.

(Current as of January 2017)