Definition
An ATC authorization for an IFR aircraft to operate in visual flight rules (VFR) conditions at any appropriate VFR altitude (as specified in the regulations) above, below, or between cloud layers. The pilot remains on an IFR flight plan and continues to comply with all IFR rules except for altitude assignment, choosing instead a VFR cruising altitude that maintains required cloud clearance and visibility.
Plain English
ATC has cleared you to fly at a VFR altitude of your own choosing while still on your IFR flight plan, as long as you can stay clear of clouds and have the visibility VFR requires.
Context Anchor
Seen in IFR en route altitude discussions, especially when a pilot is above a cloud layer and may be operating under a VFR-on-top clearance.
Derivation
"On top" refers to flying on top of, between, or in clear air relative to a cloud layer. The phrase pairs that idea with "VFR conditions" to signal that, although the flight is IFR, the pilot will pick an altitude where visual flight rules can be met.
Why Pilots Care
Allows selection of smoother or more fuel-efficient altitudes above cloud layers while remaining under positive IFR control.
Grounding Statement
Picture climbing through a gray cloud layer, then breaking out into clear air with blue sky above and a solid cloud deck below.
Intuition Check
Do not read “on top” as meaning the whole route is VFR from ground to sky. It means the conditions where the airplane is, above the cloud layer, are good enough for VFR flight.
Example Sentence 1
After climbing through a thin layer, the pilot requested VFR conditions on top to get a smoother ride between cloud decks.
Example Sentence 2
Once established in VFR conditions on top, the flight continued on the IFR routing with improved visibility and smoother air.