Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Private
Flight Crew Last 90 Days 10; Flight Crew Total 840; Flight Crew Type 200
Communication Breakdown; Confusion
ATC Issue All Types; Conflict NMAC
Air Traffic Control Issued New Clearance
Procedure
Controller directed me to descend to FL230 from FL250 then switched me to another Controller. I checked in with the new Controller and let him know I was leaving 250 for 230. He acknowledged my check in. Then called out traffic. I looked for traffic; but could not see it until it passed under my left wing and then saw it. I informed the Controller I had the traffic. I then noticed it was pretty close. As I was about to radio the Controller the other pilot asked if I was descending. The Controller immediately canceled my clearance and moved me back to 240. I executed his command. I do not know for sure; but the other pilot said my aircraft came within 500 FT of his.
A single engine pilot was cleared to FL230 from FL250 and during descent traffic was called out which he did not see until it passed beneath him less than 500 FT. ATC recleared the pilot to FL240.