Definition
A flight condition in which the aircraft is not undergoing any change in speed or direction — meaning airspeed is constant and the flight path is steady, with all forces acting on the aircraft in equilibrium.
Plain English
The aircraft is flying steadily, not speeding up, slowing down, climbing harder, descending harder, or turning. Speed and direction are holding constant.
Context Anchor
Seen in aircraft performance discussions, especially when comparing how much power is needed at different airspeeds in the region of reversed command.
Derivation
‘Accelerate’ comes from the Latin accelerare, meaning ‘to hasten’ or ‘to speed up.’ In physics, acceleration includes any change in speed or direction, not just speeding up. So ‘unaccelerated’ means no change is occurring in either — the aircraft is in steady flight.
Why Pilots Care
It explains why more power is required to hold level flight as speed decreases behind the power curve.
Grounding Statement
Picture the airplane trimmed and steady, holding one airspeed and one path without speeding up, slowing down, or turning.
Intuition Check
Unaccelerated does not mean the airplane is stopped or has no power. It means the airplane’s speed and path are not changing at that moment.
Example Sentence 1
In straight-and-level unaccelerated flight, lift equals weight and thrust equals drag.
Example Sentence 2
The power curve shows the minimum power needed for an unaccelerated condition in level flight at each airspeed.