TERCOM

Terrain contour matching, or TERCOM, is a navigation system used primarily by cruise missiles. It uses a contour map of the terrain that is compared with measurements made during flight by an on-board radar altimeter. A TERCOM system considerably increases the accuracy of a missile compared with inertial navigation systems (INS). The increased accuracy allows a TERCOM-equipped missile to fly closer to obstacles and at generally lower altitudes, making it harder to detect by ground radar.

Missiles that employ TERCOM navigation
The cruise missiles that employ a TERCOM system include:
 * Supersonic Low Altitude Missile project (early version of TERCOM was slated to be used in this never-built missile)
 * AGM-86B (United States)
 * AGM-129 ACM (United States)
 * BGM-109 Tomahawk (some versions, United States)
 * C-602 anti-ship & land attack cruise missile (China)
 * Kh-55 Granat NATO reporting name AS-15 Kent (Soviet Union)
 * Newer Russian cruise missiles, such as Kh-101 and Kh-555 are likely to have TERCOM navigation, but little information is available about these missiles
 * C-802 or YJ-82 NATO reporting name CSS-N-8 Saccade (China) – it is unclear if this missile employs TERCOM navigation
 * Hyunmoo III (South Korea)
 * DH-10 (China)
 * Babur (Pakistan) land attack cruise missile
 * Ra'ad (Pakistan) air-launched cruise missile
 * Naval Strike Missile (anti-ship and land attack missile, Norway)
 * SOM (air-launched cruise missile, Turkey)
 * Hongniao 1/2/3, Chinese cruise missiles
 * 9K720 Iskander (short-range ballistic missile and cruise missile variants, Russia)
 * Storm Shadow cruise missile (UK/France)
 * Taurus KEPD 350, German/Swedish cruise missile