Narrative:

During the descent from cruise to approach we had a possible altitude deviation over brusr intersection. We were initially given a pilot's discretion descent to FL240 and cleared to the drake VOR. I checked the legs page of the FMC to verify we had brusr at 250 degrees/12000 ft and to input the intended landing runway. The brusr restr was correct from when the initial routing was input to the FMC on the ground in las. I still had to input the landing runway which I did from the departure/arrival page of the FMC. When I entered that page I noticed that the brusr STAR was not active, so I activated it and put in the desired approach as well. I then went to the legs page to verify it with the chart and remove any discontinuities. I removed the one discontinuity and verified everything else was correct. I did not change the brusr restrs. I started the descent to FL240 based on the FMC calculated top of descent. As I started down I noticed the vertical path deviation was increasing, saying we were above the desired flight path. It was increasing much more rapidly than it should have, given the 2800 FPM descent that I was flying. About that time we were cleared direct to brusr, 'cleared direct brusr, cross brusr at 12000 ft and 250 KTS.' since we were initially going directly to drake and about 1300 ft high (but correcting) to the desired flight path, this short cut would make us higher. I increased airspeed and rate of descent and reestablished the desired descent path. It appeared that it would not be a problem and I was comfortable with making the restr based on the FMC information. About that time the captain went off frequency to pick up ATIS. There were no communications with center while the captain was off frequency. After the captain returned and we were handed off to phx approach we realized that we were about 5-6 NM from brusr and at FL210, but yet we were right on the FMC calculated descent profile. The captain called approach to get relief for the crossing restr, but before he even asked for it approach cleared us to 'descend and maintain 8000 ft and not to worry about the brusr restr. The rest of the flight was normal. The cause of this potential deviation was my fault. I placed too much reliance on the FMC generated descent path, which was obviously wrong, without adequately backing up my position with raw data. A contributing factor was the hazy day in the phx area, eliminating the normal visual cues that are helpful in this situation. Another factor was the FMC dropped the crossing restr at brusr while I programmed in the desired runway and the STAR giving me a descent profile to the runway instead of to brusr. To prevent this from occurring again, I will more carefully monitor/backup the FMC data with raw data, and double-check that the FMC doesn't change/drop important intxns/restrs when I add the desired information.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737-300 MISSES XING RESTR DURING STAR INTO PHX.

Narrative: DURING THE DSCNT FROM CRUISE TO APCH WE HAD A POSSIBLE ALTDEV OVER BRUSR INTXN. WE WERE INITIALLY GIVEN A PLT'S DISCRETION DSCNT TO FL240 AND CLRED TO THE DRAKE VOR. I CHKED THE LEGS PAGE OF THE FMC TO VERIFY WE HAD BRUSR AT 250 DEGS/12000 FT AND TO INPUT THE INTENDED LNDG RWY. THE BRUSR RESTR WAS CORRECT FROM WHEN THE INITIAL ROUTING WAS INPUT TO THE FMC ON THE GND IN LAS. I STILL HAD TO INPUT THE LNDG RWY WHICH I DID FROM THE DEP/ARR PAGE OF THE FMC. WHEN I ENTERED THAT PAGE I NOTICED THAT THE BRUSR STAR WAS NOT ACTIVE, SO I ACTIVATED IT AND PUT IN THE DESIRED APCH AS WELL. I THEN WENT TO THE LEGS PAGE TO VERIFY IT WITH THE CHART AND REMOVE ANY DISCONTINUITIES. I REMOVED THE ONE DISCONTINUITY AND VERIFIED EVERYTHING ELSE WAS CORRECT. I DID NOT CHANGE THE BRUSR RESTRS. I STARTED THE DSCNT TO FL240 BASED ON THE FMC CALCULATED TOP OF DSCNT. AS I STARTED DOWN I NOTICED THE VERT PATH DEV WAS INCREASING, SAYING WE WERE ABOVE THE DESIRED FLT PATH. IT WAS INCREASING MUCH MORE RAPIDLY THAN IT SHOULD HAVE, GIVEN THE 2800 FPM DSCNT THAT I WAS FLYING. ABOUT THAT TIME WE WERE CLRED DIRECT TO BRUSR, 'CLRED DIRECT BRUSR, CROSS BRUSR AT 12000 FT AND 250 KTS.' SINCE WE WERE INITIALLY GOING DIRECTLY TO DRAKE AND ABOUT 1300 FT HIGH (BUT CORRECTING) TO THE DESIRED FLT PATH, THIS SHORT CUT WOULD MAKE US HIGHER. I INCREASED AIRSPD AND RATE OF DSCNT AND REESTABLISHED THE DESIRED DSCNT PATH. IT APPEARED THAT IT WOULD NOT BE A PROB AND I WAS COMFORTABLE WITH MAKING THE RESTR BASED ON THE FMC INFO. ABOUT THAT TIME THE CAPT WENT OFF FREQ TO PICK UP ATIS. THERE WERE NO COMS WITH CTR WHILE THE CAPT WAS OFF FREQ. AFTER THE CAPT RETURNED AND WE WERE HANDED OFF TO PHX APCH WE REALIZED THAT WE WERE ABOUT 5-6 NM FROM BRUSR AND AT FL210, BUT YET WE WERE RIGHT ON THE FMC CALCULATED DSCNT PROFILE. THE CAPT CALLED APCH TO GET RELIEF FOR THE XING RESTR, BUT BEFORE HE EVEN ASKED FOR IT APCH CLRED US TO 'DSND AND MAINTAIN 8000 FT AND NOT TO WORRY ABOUT THE BRUSR RESTR. THE REST OF THE FLT WAS NORMAL. THE CAUSE OF THIS POTENTIAL DEV WAS MY FAULT. I PLACED TOO MUCH RELIANCE ON THE FMC GENERATED DSCNT PATH, WHICH WAS OBVIOUSLY WRONG, WITHOUT ADEQUATELY BACKING UP MY POS WITH RAW DATA. A CONTRIBUTING FACTOR WAS THE HAZY DAY IN THE PHX AREA, ELIMINATING THE NORMAL VISUAL CUES THAT ARE HELPFUL IN THIS SIT. ANOTHER FACTOR WAS THE FMC DROPPED THE XING RESTR AT BRUSR WHILE I PROGRAMMED IN THE DESIRED RWY AND THE STAR GIVING ME A DSCNT PROFILE TO THE RWY INSTEAD OF TO BRUSR. TO PREVENT THIS FROM OCCURRING AGAIN, I WILL MORE CAREFULLY MONITOR/BACKUP THE FMC DATA WITH RAW DATA, AND DOUBLE-CHK THAT THE FMC DOESN'T CHANGE/DROP IMPORTANT INTXNS/RESTRS WHEN I ADD THE DESIRED INFO.

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.