Date: 201205
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: Super King Air 200
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Distraction; Time Pressure
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: I was en route in a King Air 200 on an instrument flight plan in good VMC. I had filed for FL230. Every controller had step climbed me; usually a thousand feet at a time; and this step climbing continuing sort of like happens when following another airplane same direction. I was still being step climbed 25 minutes into the flight; which I thought was unusual. When it came time to switch Centers; the Controller told me the next Center wouldn't answer him in order to take the hand-off; but he gave me the frequency and said I should just go ahead and contact them myself. The next Center answered me right away and then cleared me from 13;000 to FL210. After a while had a feeling that communications between ATC and me and ATC and other aircraft were very strange during this flight or there were some sort of technical issues occurring or something. I know ordinarily a delay of a response when checking in sometimes means a change of shift briefing is happening or the Controller is temporarily on the land line etc; but I thought things just didn't feel right. Then maybe it was just because it was a slow afternoon; I don't know. There were very few airplanes and very little talk but even during initial call-ups by other planes I noticed the controllers seemed preoccupied with something else. I don't know really... it was just a distinct feeling. Climbing through about FL198 FT for FL230; to the best of my recollection; the Controller suddenly told me to stop and level off at FL200 which I did. I wondered why because I hadn't heard any other planes on our frequency that could have caused a conflict. As I said it was pretty quiet. A few minutes later the controller then cleared me from FL200 to FL230. Climbing through 20;900 he abruptly said something like 'King Air X; descend immediately to FL200.' I didn't question him as to the reason; I just nose the plane over as I hit 21;100 and started back down; trying not to lift my passengers off their seats. Then he said that I should 'expedite my climb' which didn't make sense; but I responded with something like 'I've already started down.' Then he asked me to say my altitude and I believe I said 'descending out of FL210.' I was trying to increase the rate if descent as best I could when an airplane went whizzing by my windshield close enough to hear him. I don't know what type and I can't tell with any certainty how close because I just saw him for a moment; but he was above and ahead moving right to left. It was one of those things that was such a shock that I couldn't believe it and wondered what the heck had just happened. What made it even spookier was that the Controller never said anything more period. I've occasionally had controllers call traffic alerts even after-the-fact; but nothing at all was said. The traffic was never called.  The other plane never said anything. It was quite surrealistic. I think there was nothing more said until the hand-off to the next sector several minutes later. And then that Controller treated me with extreme courtesy as if he was personally happy I was still alive. I was still sitting there wondering what had happened; but I didn't think it was something appropriate to discuss on the radio. I also started thinking that there was no way my passenger could have not seen that other plane; and no excuse or explanation on my part was going to keep my from getting fired. As far as a TCAS alert; I noticed that I was not getting any traffic information on a flight earlier in the day. I called the pilot who usually flies this airplane and told him that the TCAS did not appear to be working and he told me that was because one of the TCAS system components was in the avionics shop; so that explained that. When I think back on this; I believe that any one of a number of other traffic avoidance resolutions would have been better that what I was told to do. If I had been advised of the converging airplane I would have been looking specifically for him in order to get visual contact with it immediately if not sooner. If I had been warned that he was that close; converging at the same altitude; the urgency would have been even greater. If the controller had said turn right immediately; or turn left; or break right or left; or expedite climb or ANYTHING instead of telling me to stop my climb and descend which in actuality caused me to be around FL210 for the longest duration possible; it would have been better than what happened. If he had not said anything and I had just been allowed to continue my climb I would have be 500 FT above the other plane when we crossed paths. If the Controller had told me to expedite the climb I could have been over a thousand foot above him. It was a bad situation made worse by the wrong 'resolution.' As far as me personally; I don't think I alone could have done a single thing to have completely avoided this close call. We were converging at an angle so that the other plane was probably hidden from my line of site right; behind the solid area between the left and right windshield sections; and I couldn't see him coming. I know that without a doubt this is the closest I have been to another airplane in flight except while in formation flight; and the closest I have ever been to having a mid-air collision in 36 years as a professional pilot. I'm just happy to be here.




Synopsis: A King Air pilot reported a near miss at FL210 when ATC issued a climb clearance to FL230 then abruptly canceled the climb and ordered a descent after he was above FL210; but did not issue any traffic alerts.