Narrative:

We departed las on the mead 2 SID, peach springs (pgs) transition. Approaching our assigned altitude of FL290 at pgs, we were asked if we could be level at FL330 in 3 mins or less, if so cleared. We said yes and were cleared to FL330 to be 'level in 3 mins or less.' I continued the climb and as we approached the VOR at FL292, we were reclred to 'cross 10 DME east of GPS at FL330,' which we acknowledged. I immediately increased the climb rate, but soon discovered I could not sustain the necessary climb and maintain acceptable airspeed. A decrease in climb resulted in our crossing the 10 DME point at FL327. The controller queried us about our mode C, and we reported approaching FL328, the traffic in sight, low at 1 O'clock position (no factor), and that we were slow. The traffic was never reported to us and no TCASII TA was received. Shortly thereafter, the controller advised us they had had a loss of separation alarm and a phone call to ZLA would be required. Hindsight being a great teacher, we never should have accepted the initial clearance to FL330. Once cleared, we never should have accepted the initial clearance to FL330. Once cleared, we never should have accepted a change of clearance, and finally, having done that, we should have given up trying to make it, and reported we might not make FL330 by 10 DME in a timely manner. Contributing factor: the change of a workable clearance to one that proved unworkable. Supplemental information from acn 504706: my judgement of the aircraft performance capabilities and likelihood of reaching the crossing restr were, obviously, in error. Could have avoided the conflict by not accepting the clearance initially, or at least rejecting the amended climb clearance. And, as a minimum, I should have notified ATC of the decreased climb and that we might not meet our climb restr. I will certainly take a little more time to consider climb/descent capabilities before accepting that type of clearance in the future.

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Original NASA ASRS Text

Title: MD82 FLC UNDERESTIMATE ACFT PERFORMANCE CAPABILITY AND MISS XING RESTR AND CONFLICT WITH ANOTHER ACFT.

Narrative: WE DEPARTED LAS ON THE MEAD 2 SID, PEACH SPRINGS (PGS) TRANSITION. APCHING OUR ASSIGNED ALT OF FL290 AT PGS, WE WERE ASKED IF WE COULD BE LEVEL AT FL330 IN 3 MINS OR LESS, IF SO CLRED. WE SAID YES AND WERE CLRED TO FL330 TO BE 'LEVEL IN 3 MINS OR LESS.' I CONTINUED THE CLB AND AS WE APCHED THE VOR AT FL292, WE WERE RECLRED TO 'CROSS 10 DME E OF GPS AT FL330,' WHICH WE ACKNOWLEDGED. I IMMEDIATELY INCREASED THE CLB RATE, BUT SOON DISCOVERED I COULD NOT SUSTAIN THE NECESSARY CLB AND MAINTAIN ACCEPTABLE AIRSPD. A DECREASE IN CLB RESULTED IN OUR XING THE 10 DME POINT AT FL327. THE CTLR QUERIED US ABOUT OUR MODE C, AND WE RPTED APCHING FL328, THE TFC IN SIGHT, LOW AT 1 O'CLOCK POS (NO FACTOR), AND THAT WE WERE SLOW. THE TFC WAS NEVER RPTED TO US AND NO TCASII TA WAS RECEIVED. SHORTLY THEREAFTER, THE CTLR ADVISED US THEY HAD HAD A LOSS OF SEPARATION ALARM AND A PHONE CALL TO ZLA WOULD BE REQUIRED. HINDSIGHT BEING A GREAT TEACHER, WE NEVER SHOULD HAVE ACCEPTED THE INITIAL CLRNC TO FL330. ONCE CLRED, WE NEVER SHOULD HAVE ACCEPTED THE INITIAL CLRNC TO FL330. ONCE CLRED, WE NEVER SHOULD HAVE ACCEPTED A CHANGE OF CLRNC, AND FINALLY, HAVING DONE THAT, WE SHOULD HAVE GIVEN UP TRYING TO MAKE IT, AND RPTED WE MIGHT NOT MAKE FL330 BY 10 DME IN A TIMELY MANNER. CONTRIBUTING FACTOR: THE CHANGE OF A WORKABLE CLRNC TO ONE THAT PROVED UNWORKABLE. SUPPLEMENTAL INFO FROM ACN 504706: MY JUDGEMENT OF THE ACFT PERFORMANCE CAPABILITIES AND LIKELIHOOD OF REACHING THE XING RESTR WERE, OBVIOUSLY, IN ERROR. COULD HAVE AVOIDED THE CONFLICT BY NOT ACCEPTING THE CLRNC INITIALLY, OR AT LEAST REJECTING THE AMENDED CLB CLRNC. AND, AS A MINIMUM, I SHOULD HAVE NOTIFIED ATC OF THE DECREASED CLB AND THAT WE MIGHT NOT MEET OUR CLB RESTR. I WILL CERTAINLY TAKE A LITTLE MORE TIME TO CONSIDER CLB/DSCNT CAPABILITIES BEFORE ACCEPTING THAT TYPE OF CLRNC IN THE FUTURE.

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.