In a previous article, "Frode Berg" said:
I did not know this.

On all the definitions of various air classes I've seen, all have stated
"prohibited for VFR" on the class A airspace.

Are you sure about this?

What's the source?

In the Canadian regulations, it says

601.06(1) No person shall operate a VFR aircraft in Class A airspace
unless the aircraft is operated in accordance with an authorization
issued by the Minister.
(2) The Minister may issue an authorization referred to in
subsection (1) where the operation of the aircraft is in the public
interest and not likely to affect aviation safety.

In the FARs, it says:

Section 91.135: Operations in Class A airspace.

Except as provided in paragraph (d) of this section, each person operating
an aircraft in Class A airspace must conduct that operation under
instrument flight rules (IFR) and in compliance with the following:

(a) Clearance. Operations may be conducted only under an ATC clearance
received prior to entering the airspace.

(b) Communications. Unless otherwise authorized by ATC, each aircraft
operating in Class A airspace must be equipped with a two-way radio
capable of communicating with ATC on a frequency assigned by ATC. Each
pilot must maintain two-way radio communications with ATC while operating
in Class A airspace.

(c) Transponder requirement. Unless otherwise authorized by ATC, no person
may operate an aircraft within Class A airspace unless that aircraft is
equipped with the applicable equipment specified in §91.215.

(d) ATC authorizations. An operator may deviate from any provision of this
section under the provisions of an ATC authorization issued by the ATC
facility having jurisdiction of the airspace concerned. In the case of an
inoperative transponder, ATC may immediately approve an operation within a
Class A airspace area allowing flight to continue, if desired, to the
airport of ultimate destination, including any intermediate stops, or to
proceed to a place where suitable repairs can be made, or both. Requests
for deviation from any provision of this section must be submitted in
writing, at least 4 days before the proposed operation. ATC may authorize
a deviation on a continuing basis or for an individual flight.

Note that both regulations have an "out" that allows you to operate in
Class A under VFR if you have authorization. Like I said before, I've
heard of these authorizations being granted to sailplanes trying to reach
high altitudes on mountain waves.

--
Paul Tomblin http://xcski.com/blogs/pt/
"We sealed our federal pact without bloodshed and without exploitation of
the weak by the strong. All it took was fairness, justice and some
compromises on both sides." - George-Etienne Cartier.