On Tue, 25 Jan 2005 21:45:36 GMT, jsmith wrote:

Domestic Reduced Vertical Separation M?? begins at FL280.
Prior to January 20, 2005, vertical separation between aircraft above
FL280 was 2000 feet. As of 20 January 2005, the vertical separation
between aircraft at FL280 and above is 1000 feet. Only aircraft properly
equipped for DRVSM are permitted to fly above FL280.


Thanks.
z