Definition
A vertical navigation function in which the flight management system or GPS computes and displays a recommended descent path to help the pilot manage altitude on an approach or arrival, but does not provide approved vertical guidance for the approach itself. The pilot remains responsible for complying with all published altitude restrictions using the primary altimeter, and the displayed path is for situational awareness only.
Plain English
The aircraft's computer shows you a suggested up-or-down path to follow, but it is only a helpful hint. You still have to fly the published altitudes yourself using the regular altimeter -- the path on the screen is not officially approved guidance.
Context Anchor
Seen on GPS or flight management system displays during instrument approaches or descents where the equipment provides a suggested vertical path.
Derivation
Advisory comes from the Latin advisare, meaning to give counsel or recommendation -- something offered for consideration, not a binding instruction. That is exactly the role this VNAV function plays: it advises, it does not command or certify.
Why Pilots Care
Misuse can result in altitude deviations or failure to meet step-down fixes, since the guidance is not certified for primary navigation.
Grounding Statement
Treat advisory VNAV as helpful guidance on the screen, not as permission to descend.
Intuition Check
Advisory does not mean approved, required, or controlling here. It means the system is offering helpful information, while the published procedure altitudes still govern what you may do.
Example Sentence 1
The crew used advisory VNAV to plan a smooth descent into the terminal area, but cross-checked each step-down altitude against the approach chart.
Example Sentence 2
Although advisory VNAV showed a continuous 3-degree path, the pilot leveled at the published crossing restriction before continuing descent.