Patent ID: 8515600

Claim:
In an aircraft including a forward-looking radar system configured to transmit and receive forward radar signals, a downward-looking radar system, and a display for receiving a display signal representative of a terrain, a terrain awareness system comprising: a forward-looking terrain logic configured to be in communication with the forward-looking radar system and the downward-looking radar system, wherein the forward-looking terrain logic receives an altitude derived from a downward-looking radar signal from the downward-looking radar system, wherein the altitude represents a first distance between the terrain below the aircraft at a point where the downward looking radar signal strikes the terrain and the forward-looking terrain logic determines a second distance to a terrain cell from data derived from the forward radar signals, the terrain cell being in forward line of site of the aircraft, wherein the forward-looking terrain logic provides a warning if the altitude is less than threshold height, or if the second distance is less than a threshold distance, wherein the warning is provided without using a stored terrain data base.