Narrative:

During descent into las, ZLA issued us a crossing restr of 10000 ft MSL at 40 mi east of las. As the PF, I initiated the appropriate rate of descent (based on my calculations) so as to comply with this crossing restr. Subsequently, I crosschecked my descent profile against our FMS computer which indicated we were well below our target descent profile. (I later discovered this was due to the fact that the FMS computer had bypassed the 40 DME fix and was instead calculating a descent profile based on the runway 25L at las.) so I shallowed out my descent rate. A short time later, the PNF (captain) noticed that I was about 4000 ft above where I should be on the descent profile. At that point, I immediately increased my rate of descent and ended up crossing the 40 DME fix at approximately 13000 ft MSL. Just prior to reaching the 40 DME fix, the ZLA controller asked us if we were 'hurrying' (to make our descent). We responded that we were, and they switched us over to las approach control who issued us a further descent clearance to 8000 ft MSL. No mention of any potential traffic conflict was made by either center or approach control. I believe the cause of the problem was my failure to re-calculate my descent profile after the FMS showed a significantly different descent rate required. The corrective action for me will be to be more diligent in xchking FMS data to ensure these types of conflicts do not recur.

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Original NASA ASRS Text

Title: AN ACR MLG FLC WAS TOO HIGH AT A XING POINT. THE RPTR MISINTERPRETED THE FMS INFO WHICH WAS NOT REFING THE ASSIGNED XING POINT AND THOUGHT, INITIALLY, THAT HE WAS TOO LOW AND HE DECREASED HIS DSCNT RATE.

Narrative: DURING DSCNT INTO LAS, ZLA ISSUED US A XING RESTR OF 10000 FT MSL AT 40 MI E OF LAS. AS THE PF, I INITIATED THE APPROPRIATE RATE OF DSCNT (BASED ON MY CALCULATIONS) SO AS TO COMPLY WITH THIS XING RESTR. SUBSEQUENTLY, I XCHKED MY DSCNT PROFILE AGAINST OUR FMS COMPUTER WHICH INDICATED WE WERE WELL BELOW OUR TARGET DSCNT PROFILE. (I LATER DISCOVERED THIS WAS DUE TO THE FACT THAT THE FMS COMPUTER HAD BYPASSED THE 40 DME FIX AND WAS INSTEAD CALCULATING A DSCNT PROFILE BASED ON THE RWY 25L AT LAS.) SO I SHALLOWED OUT MY DSCNT RATE. A SHORT TIME LATER, THE PNF (CAPT) NOTICED THAT I WAS ABOUT 4000 FT ABOVE WHERE I SHOULD BE ON THE DSCNT PROFILE. AT THAT POINT, I IMMEDIATELY INCREASED MY RATE OF DSCNT AND ENDED UP XING THE 40 DME FIX AT APPROX 13000 FT MSL. JUST PRIOR TO REACHING THE 40 DME FIX, THE ZLA CTLR ASKED US IF WE WERE 'HURRYING' (TO MAKE OUR DSCNT). WE RESPONDED THAT WE WERE, AND THEY SWITCHED US OVER TO LAS APCH CTL WHO ISSUED US A FURTHER DSCNT CLRNC TO 8000 FT MSL. NO MENTION OF ANY POTENTIAL TFC CONFLICT WAS MADE BY EITHER CTR OR APCH CTL. I BELIEVE THE CAUSE OF THE PROB WAS MY FAILURE TO RE-CALCULATE MY DSCNT PROFILE AFTER THE FMS SHOWED A SIGNIFICANTLY DIFFERENT DSCNT RATE REQUIRED. THE CORRECTIVE ACTION FOR ME WILL BE TO BE MORE DILIGENT IN XCHKING FMS DATA TO ENSURE THESE TYPES OF CONFLICTS DO NOT RECUR.

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.