ALT XING RESTRICTION NOT MADE IN AN ALTDEV ALT UNDERSHOT INCIDENT.

Narrative

ON FLT FROM MSP-DCA; POS NW OF BUCKO INTXN ON J-34 WITH RTING OF J-34 TO BUCKO; THEN BUCKO THREE ARR TO DCA. AT CRUISE AT FL370; GIVEN CLRNC TO CROSS 25 MI W OF ESL AT FL240. AFTER INITIATING DSCNT; DETERMINED THAT XING RESTRICTION WOULD NOT BE MADE; INFORMED ATC; AND WERE GIVEN NEW ALT RESTRICTION FURTHER E. CONTRIBUTING FACTORS TO THIS INABILITY TO MAKE THE XING RESTRICTION WERE: 1. HAD COMPLETED ABOUT 1/2 OF THE 'ENCON' DATA FOR THIS LEG (THAT IS CRUISE ENG PARAMETERS WHICH WE RECORD IN OUR ACFT LOGBOOK FOR MAINT TRACKING). THE ACFT IS REQUIRED TO BE IN LEVEL FLT WITH AUTOTHRUST OFF AND ENGS STABILIZED WHILE WE RECORD THIS DATA. WE OPTED TO FINISH THIS RECORDING BEFORE BEGINNING OUR DSCNT WHICH CONSUMED 1-2 MINS ADDITIONAL TIME. 2. STRONG TAILWINDS. 3. 'CLEAN' NATURE OF OUR ACFT AND RESULTANT SLOWER RATES OF DSCNT AT NORMAL SPDS AND CONFIGNS (AS OPPOSED TO OLDER TYPES). 4. AUTOMATED NATURE OF FMS SYS. WE BEGAN OUR DSCNT WHICH INITIALLY WAS AT A SLOWER RATE THAN WE DESIRED. AFTER A MIN OR SO; WE REALIZED THAT OUR AUTOTHRUST SYS WAS STILL DISENGAGED AFTER OUR 'ENCON' PROC (2 ABOVE) UPON RE-ENGAGEMENT; NORMAL DSCNT RATE WAS RESTORED. HOWEVER; WE NOW WERE BEHIND A DSCNT SCHEDULE WHICH WOULD ALLOW US TO MAKE OUR XING RESTRICTION. WHILE THIS INABILITY TO MAKE THE XING RESTRICTION WAS A RESULT OF THE CREW'S ACTIONS; I WANT TO MAKE TWO POINTS WHICH CONTRIBUTED TO THIS: 1. THE FMS IN THIS AIRPLANE OFTEN DOES LEAD TO MOMENTARY MISUNDERSTANDING OR QUESTIONS CONCERNING THE PROGRAMMING OF THE SYS. WE ARE TRAINED TO USE THE AUTOMATIC OR PROGRAMMED SYSTEMS. WHEN THE AIRPLANE DOES NOT IMMEDIATELY RESPOND AS THE CREW INTENDED; THE TYPICAL RESPONSE IS TO PONDER WHAT PROGRAMMING STEPS WERE DONE INCORRECTLY; RATHER THAN JUST FLY IT MANUALLY WHICH OF COURSE CONSUMES TIME. 2. NEWER GENERATION ACFT DO NOT DSND AS RAPIDLY IN NORMAL CONFIGNS AS DO OLDER TYPES.