Narrative:

The incident occurred while flying a deadhead leg between psp and lbe eastbound on J96 between cim and gck. Earlier in the flight, a request was granted to climb to FL430 (opposite direction) in order to maximize range and avoid convective activity anticipated along our route in kansas. Subsequently ATC requested us to descend for opposite direction traffic converging at FL430. Under the present conditions of aircraft weight and outside air temperature, FL450 was within the climb capability of the aircraft and was preferable to FL410 for the previously mentioned reasons. Therefore, I requested FL450 and was cleared to climb. The aircraft climbed normally. However, once at FL450 it became apparent that the air temperature had increased to the extent that the aircraft would not accelerate and safety of flight dictated that a descent was necessary in order to maintain a safe flying speed. A request was made to descend to FL410. Center responded that opposite direction traffic would delay our descent and we were to maintain FL450. We repeatedly informed ATC that an immediate descent was necessary. The controller then vectored the other aircraft, but still would not permit us to descend. We again informed the controller that a descent was necessary and that we would be willing to accept a turn in order to expedite our descent clearance. ATC then vectored our aircraft but still did not grant a descent. During the entire event, we monitored the other aircraft on our TCASII. Faced with compromising safety or deviating from an ATC clearance, a decision was made to start a descent in order to accelerate. We informed ATC that we were descending and finally another controller (supervisor) broke in and acknowledged our descent 'due to temperature,' but still did not clear us to descend. We had descended to approximately FL444 when ATC finally cleared us to FL410. We were instructed to call ZAB on the ground upon landing about a possible pilot deviation. We were informed during this call that separation requirements were compromised. Apparently the required 5 mi separation was reduced to '4 point something.' during the entire event, the converging aircraft was monitored on our TCASII. No TA or RA was received from the TCASII. Deviation from an ATC clearance was necessary in the interest of safety and ATC was immediately notified of the deviation. Although I am not blaming ATC for the occurrence, I do not feel that ATC did all that was possible in an expeditious manner in order to alleviate the situation.

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Original NASA ASRS Text

Title: C650-VII CREW AT FL450 COULD NOT MAINTAIN ALT AND WERE ADVISED BY ZAB A DSCNT CLRNC COULD NOT BE GIVEN BECAUSE OF TFC.

Narrative: THE INCIDENT OCCURRED WHILE FLYING A DEADHEAD LEG BTWN PSP AND LBE EBOUND ON J96 BTWN CIM AND GCK. EARLIER IN THE FLT, A REQUEST WAS GRANTED TO CLB TO FL430 (OPPOSITE DIRECTION) IN ORDER TO MAXIMIZE RANGE AND AVOID CONVECTIVE ACTIVITY ANTICIPATED ALONG OUR RTE IN KANSAS. SUBSEQUENTLY ATC REQUESTED US TO DSND FOR OPPOSITE DIRECTION TFC CONVERGING AT FL430. UNDER THE PRESENT CONDITIONS OF ACFT WT AND OUTSIDE AIR TEMP, FL450 WAS WITHIN THE CLB CAPABILITY OF THE ACFT AND WAS PREFERABLE TO FL410 FOR THE PREVIOUSLY MENTIONED REASONS. THEREFORE, I REQUESTED FL450 AND WAS CLRED TO CLB. THE ACFT CLBED NORMALLY. HOWEVER, ONCE AT FL450 IT BECAME APPARENT THAT THE AIR TEMP HAD INCREASED TO THE EXTENT THAT THE ACFT WOULD NOT ACCELERATE AND SAFETY OF FLT DICTATED THAT A DSCNT WAS NECESSARY IN ORDER TO MAINTAIN A SAFE FLYING SPD. A REQUEST WAS MADE TO DSND TO FL410. CTR RESPONDED THAT OPPOSITE DIRECTION TFC WOULD DELAY OUR DSCNT AND WE WERE TO MAINTAIN FL450. WE REPEATEDLY INFORMED ATC THAT AN IMMEDIATE DSCNT WAS NECESSARY. THE CTLR THEN VECTORED THE OTHER ACFT, BUT STILL WOULD NOT PERMIT US TO DSND. WE AGAIN INFORMED THE CTLR THAT A DSCNT WAS NECESSARY AND THAT WE WOULD BE WILLING TO ACCEPT A TURN IN ORDER TO EXPEDITE OUR DSCNT CLRNC. ATC THEN VECTORED OUR ACFT BUT STILL DID NOT GRANT A DSCNT. DURING THE ENTIRE EVENT, WE MONITORED THE OTHER ACFT ON OUR TCASII. FACED WITH COMPROMISING SAFETY OR DEVIATING FROM AN ATC CLRNC, A DECISION WAS MADE TO START A DESCENT IN ORDER TO ACCELERATE. WE INFORMED ATC THAT WE WERE DSNDING AND FINALLY ANOTHER CTLR (SUPVR) BROKE IN AND ACKNOWLEDGED OUR DSCNT 'DUE TO TEMP,' BUT STILL DID NOT CLR US TO DSND. WE HAD DSNDED TO APPROX FL444 WHEN ATC FINALLY CLRED US TO FL410. WE WERE INSTRUCTED TO CALL ZAB ON THE GND UPON LNDG ABOUT A POSSIBLE PLTDEV. WE WERE INFORMED DURING THIS CALL THAT SEPARATION REQUIREMENTS WERE COMPROMISED. APPARENTLY THE REQUIRED 5 MI SEPARATION WAS REDUCED TO '4 POINT SOMETHING.' DURING THE ENTIRE EVENT, THE CONVERGING ACFT WAS MONITORED ON OUR TCASII. NO TA OR RA WAS RECEIVED FROM THE TCASII. DEV FROM AN ATC CLRNC WAS NECESSARY IN THE INTEREST OF SAFETY AND ATC WAS IMMEDIATELY NOTIFIED OF THE DEV. ALTHOUGH I AM NOT BLAMING ATC FOR THE OCCURRENCE, I DO NOT FEEL THAT ATC DID ALL THAT WAS POSSIBLE IN AN EXPEDITIOUS MANNER IN ORDER TO ALLEVIATE THE SIT.

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.