Narrative:

We were cleared to climb to FL330 on J42 southwest of txk VOR, when ftw center asked if we could climb to FL370 within 8 mins. After checking our performance date computer, and based upon my experience, I replied that we could, and we were cleared to climb to FL370, to be level at FL370 in 8 mins. Shortly thereafter, ftw center called again and revised our restriction to: cross 50 NM northeast of txk VOR at FL370. Climb performance was normal and on schedule until approximately FL360, when the rate of climb began dropping off. Performance at this point was still sufficient to reach FL370 by the 50 NM restriction, but thereafter continued to drop off unusually rapidly, and by FL365 it was becoming apparent that we might not reach FL370 by 50 DME. We tried to advise ftw center of our problem, but traffic on the frequency prevented us from doing so, and as the radio traffic ceased, the controller called and advised that we were at the 50 DME point and asked if we were level 370. I had to reply that west were slightly short of FL370. The controller then gave us a vector off of the airway to a heading of 120 degree. After approximately 2-3 second and 15 degree of turn, we were level at FL370, advised the center, and were cleared back on course. We continued the flight without further incident. The primary cause of the potential conflict was my misjudgment, based on experience and the pdcs data, of the climb performance of the aircraft. Considering air temperature, aircraft weight and normally performing engines, I felt we should easily have made the restriction. The aircraft is, however, approximately 20 yrs old and perhaps I should have given more weight to this age factor in estimating climb performance. The pdcs program, also, may not reflect the true age-biased performance of the aircraft. I shall in the future take a more conservative view of the performance capabilities of these airplanes, so as to avoid putting myself in this situation again.

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Original NASA ASRS Text

Title: ACR ACFT CLIMB PERFORMANCE LESS THAN WHAT FLT CREW ANTICIPATED. ARTCC CLIMB RESTRICTION NOT MET. POTENTIAL CONFLICT. LOSS OF SEPARATION AVOIDED BY CTLR ISSUING AN AVOIDANCE TURN.

Narrative: WE WERE CLRED TO CLIMB TO FL330 ON J42 SW OF TXK VOR, WHEN FTW CENTER ASKED IF WE COULD CLIMB TO FL370 WITHIN 8 MINS. AFTER CHECKING OUR PERFORMANCE DATE COMPUTER, AND BASED UPON MY EXPERIENCE, I REPLIED THAT WE COULD, AND WE WERE CLRED TO CLIMB TO FL370, TO BE LEVEL AT FL370 IN 8 MINS. SHORTLY THEREAFTER, FTW CENTER CALLED AGAIN AND REVISED OUR RESTRICTION TO: CROSS 50 NM NE OF TXK VOR AT FL370. CLIMB PERFORMANCE WAS NORMAL AND ON SCHEDULE UNTIL APPROX FL360, WHEN THE RATE OF CLIMB BEGAN DROPPING OFF. PERFORMANCE AT THIS POINT WAS STILL SUFFICIENT TO REACH FL370 BY THE 50 NM RESTRICTION, BUT THEREAFTER CONTINUED TO DROP OFF UNUSUALLY RAPIDLY, AND BY FL365 IT WAS BECOMING APPARENT THAT WE MIGHT NOT REACH FL370 BY 50 DME. WE TRIED TO ADVISE FTW CENTER OF OUR PROBLEM, BUT TFC ON THE FREQ PREVENTED US FROM DOING SO, AND AS THE RADIO TFC CEASED, THE CTLR CALLED AND ADVISED THAT WE WERE AT THE 50 DME POINT AND ASKED IF WE WERE LEVEL 370. I HAD TO REPLY THAT W WERE SLIGHTLY SHORT OF FL370. THE CTLR THEN GAVE US A VECTOR OFF OF THE AIRWAY TO A HDG OF 120 DEG. AFTER APPROX 2-3 SEC AND 15 DEG OF TURN, WE WERE LEVEL AT FL370, ADVISED THE CENTER, AND WERE CLRED BACK ON COURSE. WE CONTINUED THE FLT WITHOUT FURTHER INCIDENT. THE PRIMARY CAUSE OF THE POTENTIAL CONFLICT WAS MY MISJUDGMENT, BASED ON EXPERIENCE AND THE PDCS DATA, OF THE CLIMB PERFORMANCE OF THE ACFT. CONSIDERING AIR TEMP, ACFT WEIGHT AND NORMALLY PERFORMING ENGINES, I FELT WE SHOULD EASILY HAVE MADE THE RESTRICTION. THE ACFT IS, HOWEVER, APPROX 20 YRS OLD AND PERHAPS I SHOULD HAVE GIVEN MORE WEIGHT TO THIS AGE FACTOR IN ESTIMATING CLIMB PERFORMANCE. THE PDCS PROGRAM, ALSO, MAY NOT REFLECT THE TRUE AGE-BIASED PERFORMANCE OF THE ACFT. I SHALL IN THE FUTURE TAKE A MORE CONSERVATIVE VIEW OF THE PERFORMANCE CAPABILITIES OF THESE AIRPLANES, SO AS TO AVOID PUTTING MYSELF IN THIS SITUATION AGAIN.

Data retrieved from NASA's ASRS site as of August 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.