Definition
A graph that shows the relationship between two variables by plotting data points and connecting them with straight line segments. Each segment runs directly from one plotted point to the next, producing a continuous but angular line rather than a smooth curve.
Plain English
A graph made by marking dots for each measurement and joining the dots with straight lines. The result looks like a zig-zag line that rises, falls, or levels off as you move across the page.
Context Anchor
Seen in aviation textbooks, performance charts, and training materials when data points are shown as connected straight-line segments.
Derivation
The line is called 'broken' because it changes direction at each plotted point instead of flowing as a single smooth curve. Each straight segment is one piece of the 'broken' line.
Why Pilots Care
Many performance values in flight manuals are presented this way. Reading a broken-line graph correctly means tracking the segments between known data points rather than assuming a smooth curve, so you can pull accurate values for takeoff distance, fuel burn, climb rate, and similar figures.
Analogy
It works like a connect-the-dots drawing: each dot is a known value, and the straight lines show the path between them.
Intuition Check
“Broken” does not mean the graph is damaged. It means the line is made of separate straight segments with bends at the data points.
Example Sentence 1
He used the broken-line graph in the POH to find the expected fuel burn at his planned cruise altitude.
Example Sentence 2
Pilots use the broken-line graph in the weight-and-balance section to visualize how center of gravity shifts with fuel burn.