Back to allthenines original post.
The min rate of descent *is* 500fpm in the UK.
That accomodates unpressurised aircraft as well as others when descending in a stack and allows the use of procedural separation for stack management.
Enroute , pressurised aircraft that descend at that rate will penalise themselves in anything other than a quiet environment.
Unpressurised aircraft may expect their routes to be extended when the ideal descent profile is blocked by other traffic.
That's all there is to it. Anything else has to be a contract between controller and pilot to acheive a desired game plan.
[ 23 August 2001: Message edited by: hatsoff ]