Definition
The rate of change of angular (rotational) velocity over time. In flight, it refers to how quickly the rate of rotation about an aircraft's axis is increasing or decreasing, expressed in units such as degrees per second per second.
Plain English
How fast a turning or rolling motion is speeding up or slowing down. It is not the rate of turn itself, but how quickly that rate is changing.
Context Anchor
Seen in instrument flying discussions of the inner ear, especially how the body senses aircraft motion when a turn begins, changes, or stops.
Derivation
From Latin angulus (corner, angle) and accelerare (to hasten, from ad- 'toward' + celer 'swift'). Together it literally means 'hastening of an angle' — the speeding up of a rotational motion.
Why Pilots Care
Understanding angular acceleration helps pilots recognize why the body senses turns and why this can produce spatial disorientation in instrument conditions.
Analogy
If you sit in a swivel chair and someone starts spinning it, your body feels the start of the spin strongly. If the chair keeps spinning smoothly, the feeling may fade. When the chair stops, your body may feel as if it is turning the other way.
Grounding Statement
If you start rolling into a bank and the roll rate keeps increasing, you are experiencing angular acceleration; if you hold a steady roll rate, the angular acceleration is zero even though you are still rotating.
Intuition Check
Do not read “acceleration” here as only speeding up straight ahead. In this context, it means any change in turning motion, including starting, slowing, stopping, or changing direction.
Example Sentence 1
When the pilot abruptly rolled into a steep bank, the angular acceleration stimulated the semicircular canals and produced a strong sensation of turning.
Example Sentence 2
Instrument training emphasizes trusting the turn coordinator because angular acceleration sensed by the ear can be misleading.