Can anybody explain what's the point of this and in what kind of situations a pilot needs it?
ICAO Doc 9432 "Manual of Radiotelephony"
8.3.3 An aircraft may request a clearance to climb or descend maintaining own separation while in VMC, in daylight, below 10 000 feet in airspace classes D and E. The clearance shall include information on essential traffic.
P: FASTAIR 345, REQUEST VMC DESCENT TO FL 60
C: FASTAIR 345, DESCEND TO FL 60, MAINTAIN OWN SEPARATION AND VMC FROM FL 90 TO FL 70, TRAFFIC WESTBOUND FRIENDSHIP FL 80, ESTIMATING WICKEN VOR AT 07.