Patent ID: 11959729
Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
Field: Other special machines (Mechanical engineering)
Classification: CPC F  G  B | IPC F

Claim 7:
8. A non-transitory computer-readable medium or computer program product comprising:
instructions that are executable by a processor to cause a terrain-referenced navigation system to:
receive input from a radar altimeter;
match radar altimeter measurements of terrain already traversed with the stored digital terrain map in order to calculate aircraft position relative to the stored digital terrain map to determine a terrain-referenced aircraft position, the stored digital terrain map comprising a plurality of map posts of terrain elevation data;
calculate a fall line for a projectile starting from the terrain-referenced aircraft position as a launch point;
directly compare the fall line with the digital terrain map, by incrementally comparing a height of the projectile along the fall line with a height of the terrain according to the stored digital terrain map according to a coarse search of the digital terrain map and then according to a fine search of the digital terrain map in order to find an expected impact point on the terrain; and
display, to a pilot, the expected impact point on the terrain on an aircraft display;, wherein, during the coarse search of the digital terrain map, the instructions cause the terrain-referenced navigation system to:
increment along the fall line to a boundary of a map sheet, the map sheet comprising a subset of the map posts in the stored digital terrain map, the subset comprising a plurality of map posts;
calculate a maximum height of terrain in the map sheet; and
compare the height of the projectile at the map sheet boundary to the maximum height of terrain in the map sheet.