Narrative:

In cruise flight at FL350 en route from den to cyvr, was cleared on the acord arrival. Initially planned runway 8 per the most recent cyvr ATIS. As we got on the arrival, ZSE changed us to runway 26. While still at FL350, programmed acord at 12000 ft and bacon at 230 KTS. With these constraints in the FMGC, we planned a managed descent. ZSE cleared us to maintain FL310 and then cross acord at 12000 ft. We entered a managed descent which gives us 1000 FPM down until intercepting the managed descent point to acord. Descending through FL240 we realized that although the FMGC was still showing us about 2000 ft low on the profile there was no way we were going to make bacon at 230 KTS and acord at 12000 ft. We could have done either one but not both. Approaching bacon, we informed ATC of this fact. They told us we could not get relief on either constraint and gave us a new clearance which turned us out to the northeast to continue our descent which we complied with and landed uneventfully. After landing, we discussed what might have gone wrong with our managed descent. I have been on the A320 4+ yrs and the first officer 6+ yrs. Neither of us had ever seen the A320 be that far off on an altitude and airspeed constraint. We had both seen constraints drop out of the FMGC before. But after realizing we were going to be high we doublechked and both constraints were still in the FMGC and we were in the descent phase of flight. We had also programmed the descent winds while on the ground in denver and they seemed pretty close to actual. One possible additional factor is the fact that we changed databases before leaving den as the old one had expired. We spoke with cyvr ATC after this occurred and he related to me that this is a recurring problem with aircraft being too fast at bacon and too high at acord. He also stated that no one particular type of aircraft is involved, it's happening with both airbuses and boeings.

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Original NASA ASRS Text

Title: AN A320 FLT CREW COMPLAINS OF THE PROBS ENCOUNTERED IN ATTEMPTING TO FOLLOW THE DSCNT AND SPD CONSTRAINTS ON THE ACORD ARR, RWY 26 AT CYVR, BC.

Narrative: IN CRUISE FLT AT FL350 ENRTE FROM DEN TO CYVR, WAS CLRED ON THE ACORD ARR. INITIALLY PLANNED RWY 8 PER THE MOST RECENT CYVR ATIS. AS WE GOT ON THE ARR, ZSE CHANGED US TO RWY 26. WHILE STILL AT FL350, PROGRAMMED ACORD AT 12000 FT AND BACON AT 230 KTS. WITH THESE CONSTRAINTS IN THE FMGC, WE PLANNED A MANAGED DSCNT. ZSE CLRED US TO MAINTAIN FL310 AND THEN CROSS ACORD AT 12000 FT. WE ENTERED A MANAGED DSCNT WHICH GIVES US 1000 FPM DOWN UNTIL INTERCEPTING THE MANAGED DSCNT POINT TO ACORD. DSNDING THROUGH FL240 WE REALIZED THAT ALTHOUGH THE FMGC WAS STILL SHOWING US ABOUT 2000 FT LOW ON THE PROFILE THERE WAS NO WAY WE WERE GOING TO MAKE BACON AT 230 KTS AND ACORD AT 12000 FT. WE COULD HAVE DONE EITHER ONE BUT NOT BOTH. APCHING BACON, WE INFORMED ATC OF THIS FACT. THEY TOLD US WE COULD NOT GET RELIEF ON EITHER CONSTRAINT AND GAVE US A NEW CLRNC WHICH TURNED US OUT TO THE NE TO CONTINUE OUR DSCNT WHICH WE COMPLIED WITH AND LANDED UNEVENTFULLY. AFTER LNDG, WE DISCUSSED WHAT MIGHT HAVE GONE WRONG WITH OUR MANAGED DSCNT. I HAVE BEEN ON THE A320 4+ YRS AND THE FO 6+ YRS. NEITHER OF US HAD EVER SEEN THE A320 BE THAT FAR OFF ON AN ALT AND AIRSPD CONSTRAINT. WE HAD BOTH SEEN CONSTRAINTS DROP OUT OF THE FMGC BEFORE. BUT AFTER REALIZING WE WERE GOING TO BE HIGH WE DOUBLECHKED AND BOTH CONSTRAINTS WERE STILL IN THE FMGC AND WE WERE IN THE DSCNT PHASE OF FLT. WE HAD ALSO PROGRAMMED THE DSCNT WINDS WHILE ON THE GND IN DENVER AND THEY SEEMED PRETTY CLOSE TO ACTUAL. ONE POSSIBLE ADDITIONAL FACTOR IS THE FACT THAT WE CHANGED DATABASES BEFORE LEAVING DEN AS THE OLD ONE HAD EXPIRED. WE SPOKE WITH CYVR ATC AFTER THIS OCCURRED AND HE RELATED TO ME THAT THIS IS A RECURRING PROB WITH ACFT BEING TOO FAST AT BACON AND TOO HIGH AT ACORD. HE ALSO STATED THAT NO ONE PARTICULAR TYPE OF ACFT IS INVOLVED, IT'S HAPPENING WITH BOTH AIRBUSES AND BOEINGS.

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.