There is also a speed issue when inside the 30 mile radius of the Class
Bravo primary. FAR 91.117 covers that..."No person may operate an aircraft
in the air space underlying a Class B airspace area designated for an
airport or in a VFR corridor designated through such a Class B airspace
area, at an indicated airspeed of more than 200 knots.

Fred


"john smith" wrote in message
...
The regs say you must communicate, have permission, a clearance, have a
transponder, etc to fly in any Class B/C/D Airspace.
The airspace is generally defined by the airport reference point altitude
and location on the field. For example the definitions state "from the
surface to..."
What requirements are there for flying BELOW the airport surface?
I know several airports with the requisite airspace that are located above
surrounding terrain where it would be possible to fly below the airport
surface.
What say the group?