7-3-1 VFR on Top
a. You may clear an aircraft to maintain "VFR on top" if the pilot of an aircraft on an IFR flight plan requests the clearance.
MAINTAIN VFR ON TOP.
1 - When an aircraft has been cleared to maintain "VFR on top," the pilot is responsible to fly at an appropriate VFR altitude, comply with VFR visibility and distance from cloud criteria, and to be vigilant so as to see and avoid other aircraft.
2 - Although standard IFR separation is not applied, controllers shall continue to provide traffic advisories and safety alerts, and apply merging target procedures to aircraft operating VFR on top.
b. 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:
1. The pilot requests the clearance.
2. You inform the pilot of the reported height of the tops of the meteorological formation, or
3. You inform the pilot that no top report is available.
4. When necessary, you ensure separation from all other traffic for which you have separation responsibility by issuing an alternative clearance.
5. When an aircraft is climbing to and reports reaching "VFR on top," reclear the aircraft to maintain "VFR on top."
CLIMB TO AND REPORT REACHING VFR ON TOP,
TOPS REPORTED (altitude),
NO TOPS REPORTS.
IF NOT ON TOP AT (altitude), MAINTAIN (altitude), AND ADVISE.
MAINTAIN VFR ON TOP.
c. 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.
MAINTAIN VFR ON TOP AT OR ABOVE/BELOW/BETWEEN (altitudes).
"Maintain VFR on top at or above one three thousand five hundred."
"Maintain VFR on top at or below one two thousand five hundred."
"Maintain VFR on top at or between six thousand and one zero thousand."
d. 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.
IF UNABLE, (alternative procedure), AND ADVISE.
FAAO 7110.65, VFR on Top, paragraph 9-5-3.
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 CFR Part 91.159(a).
As required by FAR 91.159(a), the appropriate VFR altitudes for aircraft (not in a holding pattern of 2 minutes or less, or turning) operating more than 3,000 feet above the surface to and including 18000 feet MSL:
Magnetic courses 0° to 179° - Odd cardinal altitudes plus 500 feet; e.g., 3,500, 5,500, FL 195, 275.
Magnetic courses 180° to 359° - Even cardinal altitudes plus 500 feet; e.g., 4,500, 8,500.
VFR ON TOP CRUISING LEVELS FOR YOUR DIRECTION OF FLIGHT ARE:
More than 3,000 feet above the surface to FL 180:
ODD/EVEN ALTITUDES/FLIGHT LEVELS PLUS FIVE HUNDRED FEET.