I have used it a lot. You have more freedom to choose a cruising altitude
when on top. My most common use here in the US was two-fold...if I wanted to
punch out through a low overcast, I could simply ask ground control for a
clearance to VFR on top...the clearance would be something like "Cleared to
the Seattle VOR, climb and maintain 7000 feet; if not on top at 7000 feet
advise." Of course, I would be on top long before I got to 7000 feet...then
I would ask for a heading toward my destination "until receiving xxx VOR
suitable for navigation." This would cut the time from engine start to
enroute cruise by 25 to 50 percent. The second ploy was when I was taking
off from an airport in Eastern Washington where it was severe clear, knowing
that the Puget Sound basin was IFR. By filing for VFR-on-top I had the
freedom of taking off VFR and being VFR but I was in the system, so when I
saw the clouds beginning to peek over the top of the Cascade Mountains all I
had to do was ask the controller for a "hard altitude" to replace the VFR
altitude I had been maintaining. Bingo...I was ready to enter the terminal
area and shoot an approach with an IFR clearance.

Note that your Aussie regs, when finalized, might not match ours.

Bob Gardner

"MC" wrote in message
...
Australia is changing/rearranging its' airspace model to more closely
line-up with ICAO and also to be a _very_ close copy of the current
USA system.

Basically there will be a heck of a lot of class-E. (usually bottomed
at FL180, but in some areas down to A085).
Our radar coverage won't change much beyond the current (roughly) 200nm
band along the east and south coasts.


One of the new procedures is called 'VFR on top', whereby an IFR aircraft
can go into VMC at VFR levels and still receive traffic advisories
(but no seperation) from IFR or observed VFR traffic.

As I see it, the procedure seems odd to me, because the requesting IFR
aircraft loses the safety of being seperated by ATC.
So my questions are ;
Is 'VFR on top' used a lot in the USA ? In the rest of the world ?
What practical advantages are there from a pilots' POV ?