Definition
A symbol convention used on aircraft drawings and engineering diagrams to indicate that an angle shown in the view is more than 45 degrees from a reference line, typically the horizontal or a datum. The symbol communicates the angular relationship between two surfaces, lines, or features when the exact value is not dimensioned on the drawing.
Plain English
It is a drafting symbol used on aircraft drawings to show that the angle between two lines or surfaces is bigger than 45 degrees.
Context Anchor
Seen in aircraft drawings, maintenance instructions, diagrams, and training material where a line, part, or direction must be compared with a stated reference.
Derivation
Angle comes from a Latin word meaning “corner.” Degree comes from a Latin word meaning “step.” Together, they describe how many measured steps of opening or turn there are between two lines.
Why Pilots Care
Bank angles above 45 degrees rapidly raise stall speed and structural loads, directly affecting safety margins in maneuvering flight.
Grounding Statement
Picture two lines on a drawing meeting at a corner, leaning away from each other wider than the corner of a square — that wider opening is what this symbol marks.
Intuition Check
Do not read “greater than 45°” as “45° or more.” It means more than 45°, and the reference being measured from must be the one stated in the instruction or diagram.
Example Sentence 1
The mechanic checked the drawing and saw the symbol for an angle greater than 45° between the bracket and the firewall.
Example Sentence 2
The pilot avoided an angle greater than 45 degrees on the base-to-final turn to keep the load factor within normal limits.