Definition
A digital elevation model is a computer dataset that stores the height of the Earth's surface as a grid of elevation values referenced to a known vertical datum. In a Synthetic Vision System (SVS), the avionics use this dataset, combined with the aircraft's position, to draw a three-dimensional picture of the terrain ahead of the aircraft on the primary flight display.
Plain English
It is a digital map of the ground's shape, made of millions of height readings, that the avionics use to draw the hills, valleys, and mountains the pilot sees on the synthetic vision display.
Context Anchor
Seen in synthetic vision system discussions, especially when explaining how the system draws terrain on the cockpit display.
Derivation
Digital means stored as numbers in a computer. Elevation is the height of the ground above a reference (such as sea level). Model means a representation of something real. Together: a numerical representation of how high the ground is across an area.
Why Pilots Care
Supplies the terrain data that synthetic vision systems need to depict rising ground and obstacles, reducing the risk of controlled flight into terrain.
Grounding Statement
Picture the ground divided into many small squares, with each square carrying a number that says how high that piece of ground is.
Intuition Check
A digital elevation model is not a photograph of the ground, and it is not a perfect copy of the real world. It is stored height data that the system uses to create a terrain display.
Example Sentence 1
The synthetic vision system uses a digital elevation model to render the ridgeline ahead on the primary flight display.
Example Sentence 2
During preflight planning the pilot confirmed that the approach path was clear of obstacles shown in the digital elevation model.