You may clear an aircraft to maintain “VFR‐on‐top” if the pilot of an aircraft on an IFR flight plan requests the clearance.
You may clear an aircraft to climb through clouds, smoke, haze, or other meteorological formations and then to maintain “VFR‐on‐top” if the following conditions are met:
The pilot requests the clearance.
You inform the pilot of the reported height of the tops of the meteorological formation, or
You inform the pilot that no top report is available.
When necessary, you ensure separation from all other traffic for which you have separation responsibility by issuing an alternative clearance.
When an aircraft is climbing to and reports reaching “VFR‐on‐top,” reclear the aircraft to maintain “VFR‐on‐top.”
Do not clear an aircraft to maintain “VFR‐on‐top” between sunset and sunrise to separate holding aircraft from each other or from en route aircraft unless restrictions are applied to ensure the appropriate IFR vertical separation.
When, in your judgment, there is reason to believe that flight in VFR conditions may become impractical, issue an alternative clearance which will ensure separation from all other aircraft for which you have separation responsibility.
7-3-2. ALTITUDE FOR DIRECTION OF FLIGHT
Inform an aircraft maintaining “VFR‐on‐top” when a report indicates the pilot is not complying with 14 CFR section 91.159(a).