VFR-on-Top Restrictions:VFR-on-top is not permitted in certain airspace areas, such as Class A airspace, certain restricted areas, etc. Consequently, IFR flights operating VFR-on-top will avoid such airspace.
A VFR-On-Top clearance has its limitations. Here are a few you need to follow: Pilots may not fly below minimum en route IFR altitudes because you could crash into the terrain. Minimum en route altitudes exist regardless of IFR or VFR weather conditions and weather assigned a specific altitude or VFR conditions on top.
According to the FAA's Instrument Flying Handbook (IFH), pilots on IFR flight plans operating in VFR weather conditions may request VFR-on-top in lieu of an assigned altitude. This permits them to select an altitude or flight level of their choice (subject to any ATC restrictions).
VFR flights above FL 290 are forbidden in RVSM airspace. The maximum VFR flight level is ICAO defined. According to your national regulation (AIP), it may be different.
When can a VFR-on-Top clearance be assigned by ATC? Only upon request of the pilot when conditions are indicated to be suitable. When must a pilot fly at a cardinal altitude plus 500 feet on an IFR flight plan? When assigned a VFR-on-Top clearance.
Class B, C, D, E, and G airspace all have VFR weather minimums, but Class A is different. Since VFR travel, including SVFR, is not allowed in Class A airspace, there are no weather minimums to be aware of. All Class A flights are flown under ATC control and using instruments.
As long as you maintain the minimum VFR requirements regarding visibility and cloud clearances, you are good to go—all you need is a natural horizon. (This is not the same as “VFR-on-top,” which is actually a type of IFR clearance.) You can't see the ground, but GPS makes it easy to know where you are.
Prohibited areas contain airspace of defined dimensions identified by an area on the surface of the earth within which the flight of aircraft is prohibited. Such areas are established for security or other reasons associated with the national welfare.
Prudent pilots typically set higher weather minimums for night VFR flights. FAR 91.157—In order to get a Special VFR clearance at night, you must have an instrument rating, an instrument-equipped airplane, 1 mile visibility, be able to remain clear of clouds, and a Special VFR clearance from air traffic control.
VFR aircraft also must maintain a horizontal distance of 1sm from clouds while operating in Class E at and above 10,000ft. Below 10,000ft, the increase in TAS is reduced due to the lower altitudes. Therefore, the minimum forward flight visibility can be reduced from 5sm to 3sm.
Class D. IFR and VFR flights are permitted and all flights are provided with air traffic control service, IFR flights are separated from other IFR flights and receive traffic information in respect of VFR flights, VFR flights receive traffic information in respect of all other flights.
Separation is provided within the Class C airspace and the outer area after two-way radio communications and radar contact are established. VFR aircraft are separated from IFR aircraft within the Class C airspace by any of the following:Visual separation.500 feet vertical separation.