B737 FLC FAILED TO MEET XING RESTR WHILE ENRTE TO BWI.

Narrative

PART 121 PAX FLT DET-BWI; NIGHT VMC. I (FO) HAD JUST GIVEN THE ACFT TO THE CAPT WHILE I WAS ABOUT TO START MY MEAL. AT AN INTERMEDIATE LEVELOFF ALT OF FL250 WE HAD BEEN GIVEN A CLRNC TO CROSS MUMSY AT 15000 FT. WE BOTH CONFIRMED THE NEW ALT RESTR AND THAT IT WAS APPROPRIATELY SET UP IN THE BOX (FMC). WE WERE APPROX 40 MI AWAY; SO I KNEW I HAD ABOUT 3 MINS OR SO BEFORE WE STARTED DOWN FOR OUR RESTR (70 KT TAILWINDS/LIGHT ACFT). WE ARE STILL NOT SURE WHAT HAPPENED BUT FOR SOME REASON IT BECAME OBVIOUS THAT WE WOULD NOT BE ABLE TO MAKE OUR RESTR -- TO US AS WELL AS OUR CTLR. ATC GAVE US A HDG (VECTOR) AND TOLD US TO CONTINUE OUR DSCNT TO 12000 FT AND TO EXPEDITE THROUGH 14000 FT. WE DID. HE SAID NO PROB; AND WE CONTINUED THE FLT AS NORMAL. I HONESTLY HAVE NO IDEA WHERE WE WENT WRONG BUT I HAVE 2 THEORIES: IF THE VNAV REALIZED THAT IT CAN'T MAKE A RESTR IT WILL DISCONNECT; CAUSING THE PLTS TO DO SOMETHING ABOUT IT. BECAUSE THIS DIDN'T HAPPEN; I THINK THAT MY CAPT MAY HAVE SELECTED A HIGHER SPD FOR OUR DSCNT AT THE LAST MOMENT; WHICH WOULD HOLD OUR ACFT HIGHER LONGER. HOWEVER; HE DIDN'T TELL ME WHAT HE WAS DOING OR IN FACT WHAT WAS UNFOLDING. BY THE TIME I GOT INVOLVED; ALL OF MY VERT NAV INFO WAS SO FAR BEHIND ME THAT THERE WAS NOTHING I COULD DO TO MAKE OUR RESTR. ALSO; WE WERE CLOSE TO VMO ANYWAY; SO SOMEHOW OUR THROTTLES NEVER CAME TO IDLE. IT ALL HAPPENED SO FAST AND WE TRIED TO RECRATE AND EVALUATE WHAT HAD HAPPENED; BUT TO NO AVAIL. BEFORE WE HANDED OFF THE CTLS WE CONFIRMED WHAT WAS GOING ON; BUT I FEEL THAT AS SOON AS THE CAPT KNEW THAT SOMETHING WAS NOT AS EXPECTED; HE SHOULD HAVE MADE AN EFFORT TO BRING ME BACK INTO THE LOOP. I ALSO THINK THAT EVEN THOUGH ONE PLT HAS BEEN GIVEN THE RESPONSIBILITY TO FLY AND WORK THE RADIOS HE SHOULD HAVE TO VERIFY ALL CHANGES TO THE PNF. I ALSO FEEL THAT ATIS SHOULD ALWAYS BE PICKED UP BEFORE THE DSCNT OR AT CRUISE ALT -- REGARDLESS OF HOW CLOSE IT IS TO CHANGING. I DON'T THINK THAT THIS WAS A PLAYER HERE BUT IT'S JUST ONE LESS THING TO DO. I AM HAPPY TO SAY THAT WE MADE TIME TO DEBRIEF THE SIT AND TRIED TO COME UP WITH SOME EXPLANATIONS BUT WE WERE AT A DEAD END. SOME CONTRIBUTING FACTORS WERE THAT WE WERE 1 HR LATE; IT WAS LATE AT NIGHT AND WE WERE GOING AS FAST AS POSSIBLE; SO BY THE TIME WE FIGURED IT OUT THERE WASN'T MUCH WE COULD DO. I DON'T KNOW WHAT THE FAA OR NASA CAN LEARN FROM THIS; BUT I KNOW I DID.