Plain English Meaning

Anything on the takeoff surface that isn't smooth and flat — bumps, dips, soft patches, debris, or tall grass that the wheels have to roll over or through.

Full Definition

Bumps, ruts, holes, soft spots, rocks, tall grass, or other uneven features on the runway or takeoff surface that disturb the airplane's smooth ground roll and can damage the airplane, increase rolling resistance, or upset directional control.

Context Anchor

Used during soft-field and rough-field takeoff discussions, especially while the airplane is accelerating on an unpaved, grass, gravel, or damaged surface.

Derivation

Irregular comes from a Latin idea meaning “not according to rule” or “not even.” In this aviation use, the surface is not smooth and uniform, so the airplane may not roll over it evenly.