Definition
The phase of takeoff during which the airplane accelerates along the runway from a standstill until the wheels leave the ground. It begins when takeoff power is applied and ends at the moment of liftoff.
Plain English
The part of takeoff where the airplane is still on the runway, speeding up, before the wheels come off the ground.
Context Anchor
You encounter this term when learning takeoff technique, runway length planning, and takeoff performance.
Derivation
Roll' here refers to the wheels rolling along the runway. The aircraft is literally rolling — not yet flying — so the term names the rolling phase of the takeoff.
Why Pilots Care
Directly determines the runway length required for a safe takeoff and is a key factor in go/no-go decisions.
Intuition Check
Do not confuse “roll” here with rolling the airplane left or right in flight. In this term, “roll” means the airplane is moving on its wheels along the ground.
Example Sentence 1
On a hot day at a high-elevation airport, the takeoff roll was noticeably longer than usual.
Example Sentence 2
On a hot day the ground roll increased noticeably, so the pilot waited for cooler air before departing.