B757 CREW MISSES XING RESTR.

Narrative

I WAS CAPT ON ACFT X FROM DTW TO LGA ON SEP/XA/99. WE WERE FLYING THE MILTON 3 ARR AT 12000 FT AND HAD BEEN ASSIGNED TO CROSS BEUTY AS PUBLISHED AT 10000 FT. WE HAD ENTERED THIS XING AND ALL OTHERS PRIOR TO TOP OF DSCNT. THE DSCNT HAD BEEN NORMAL WITH THE AUTOPLT ON AND BEING OPERATED IN VNAV AND LNAV. WE LEVELED AT 12000 FT TO CROSS VIBES AS PUBLISHED AND RESET THE CRUISE ALT TO 12000 FT TO GET A NEW TOP OF DSCNT POINT FOR THE XING RESTR AT BEUTY. I VERIFIED THAT WE WERE IN VNAV AND LNAV AND MONITORED THE INSTS FOR THE ARR. THE ACFT STARTED A DSCNT AT THE TOP OF DSCNT POINT. WE HAD DSNDED ABOUT 500 FT WHEN THE ACFT CAME OUT OF VNAV FOR NO KNOWN REASON. I SELECTED VNAV AGAIN AND MY DSCNT PAGE SHOWED THAT WE WERE ON PROFILE AND MY ALT RANGE ARC AGREED. I HAD SELECTED A LARGER THAN NORMAL SCALE ON THE HSI TO SEE THE REMAINDER OF THE ARR. I FELT THAT THE ACFT WOULD HAVE A TOUGH TIME MAKING THE REMAINDER OF THE DSCNT IN THE DISTANCE REMAINING AND SELECTED FLT LEVEL CHANGE TO 10000 FT. WHILE I WAS SELECTING SPD BRAKES TO INCREASE THE DSCNT RATE; I CHKED THE FO'S PROGRESS PAGE AND IT DID SHOW WE WERE HIGH FOR THE XING AT BEUTY. I CROSSED THE BEUTY INTXN APPROX 500 FT HIGH AND THERE WERE NO CONFLICTS. I HAVE FLOWN THE B757 FOR MANY YRS AND HAVE SEEN MANY GLITCHES BUT I HAVE NOT EXPERIENCED THIS ONE BEFORE. I DO KNOW THAT THE B757 CUTS ALL XING RESTRS VERY CLOSE AND YOU HAVE VERY LITTLE TIME TO CORRECT ANY PROBS ONCE THEY OCCUR. IN THE FUTURE; I WILL RELY ON A SMALLER SCALE FOR A BETTER FEELING OF THE DISTANCE REMAINING TO THE NEXT FIX. I WILL ALSO MAKE A PRACTICE OF USING THE INFO ON THE FO'S PROGRESS PAGE TO BACK UP THE INFO ON MY DSCNT PAGE AND HSI. I FEEL THAT IF I HAD CAUGHT THIS JUST A LITTLE EARLIER I WOULD HAVE MADE THE RESTR.