Narrative:

We were level at FL430 eastbound. ATC asked us to either climb to FL450 or descend to FL410 due to traffic coming our way at FL430. Prior to this, we had determined that for our weight and the outside air temperature, we could be able to climb to FL450 if needed. I (captain) was filling out paperwork and programming the FMS. The copilot, who was the PF, stated that we would climb to FL450. At about FL446, the aircraft was unable to climb any further. We informed ATC that we would need a descent and would be unable to stay where we were. ATC instructed us to descend to FL410 and to turn 40 degrees left. While descending, we apparently came within 1.5 mi and 1200 ft of the traffic at FL430. We had the other aircraft insight, and he also stated that he had us in sight. We received a TA on the TCASII as we were maneuvering. ATC later gave us a number to call and informed us of a possible pilot deviation. At no time did I feel the safety of flight was compromised. I feel that I should have monitored more what the other pilot was doing, and we should have paid more attention to the temperature as we climbed, as I feel that was the determining factor in our inability to climb any further.

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Original NASA ASRS Text

Title: A C560XL CREW IS UNABLE TO CLB TO A CLRED ALT OF FL450 AS REQUESTED TO CLR OPPOSITE DIRECTION TFC. A CONFLICT RESULTS.

Narrative: WE WERE LEVEL AT FL430 EBOUND. ATC ASKED US TO EITHER CLB TO FL450 OR DSND TO FL410 DUE TO TFC COMING OUR WAY AT FL430. PRIOR TO THIS, WE HAD DETERMINED THAT FOR OUR WT AND THE OUTSIDE AIR TEMP, WE COULD BE ABLE TO CLB TO FL450 IF NEEDED. I (CAPT) WAS FILLING OUT PAPERWORK AND PROGRAMMING THE FMS. THE COPLT, WHO WAS THE PF, STATED THAT WE WOULD CLB TO FL450. AT ABOUT FL446, THE ACFT WAS UNABLE TO CLB ANY FURTHER. WE INFORMED ATC THAT WE WOULD NEED A DSCNT AND WOULD BE UNABLE TO STAY WHERE WE WERE. ATC INSTRUCTED US TO DSND TO FL410 AND TO TURN 40 DEGS L. WHILE DSNDING, WE APPARENTLY CAME WITHIN 1.5 MI AND 1200 FT OF THE TFC AT FL430. WE HAD THE OTHER ACFT INSIGHT, AND HE ALSO STATED THAT HE HAD US IN SIGHT. WE RECEIVED A TA ON THE TCASII AS WE WERE MANEUVERING. ATC LATER GAVE US A NUMBER TO CALL AND INFORMED US OF A POSSIBLE PLTDEV. AT NO TIME DID I FEEL THE SAFETY OF FLT WAS COMPROMISED. I FEEL THAT I SHOULD HAVE MONITORED MORE WHAT THE OTHER PLT WAS DOING, AND WE SHOULD HAVE PAID MORE ATTN TO THE TEMP AS WE CLBED, AS I FEEL THAT WAS THE DETERMINING FACTOR IN OUR INABILITY TO CLB ANY FURTHER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.