Definition
An incorrect display on the vertical speed indicator (VSI) where the needle shows the opposite direction of actual vertical movement, typically caused by a blocked or damaged static port or a defective instrument. For example, the VSI may show a climb when the aircraft is actually descending, or vice versa.
Plain English
When the climb-and-descent gauge shows the wrong direction — for instance, pointing up when you're actually going down. It usually means something is wrong with the instrument or its air supply.
Context Anchor
Seen when using the vertical speed indicator during straight-and-level instrument flight and during small pitch corrections.
Derivation
Reverse comes from a Latin idea meaning “turned back” or “turned the other way.” Indication comes from a Latin idea meaning “to point out.” Together, the term means a showing that points the other way from what is actually happening or expected.
Why Pilots Care
Anticipating this brief reversal prevents over-correction when establishing a new vertical speed.
Grounding Statement
A reverse indication is a short-lived opposite reading, not proof that the airplane has truly changed direction vertically.
Intuition Check
Do not assume “reverse indication” means the airplane is flying backward or that the VSI has completely failed. Here it means the VSI briefly shows the opposite vertical direction before the correct trend becomes clear.
Example Sentence 1
During the instrument scan, the pilot noticed a reverse indication on the VSI when the altimeter showed a steady climb but the VSI needle pointed down.
Example Sentence 2
During level-off from descent, the pilot ignored the momentary reverse indication on the VSI and waited for the needle to stabilize.