DC9-30 CREW HAD ALT UNDERSHOOT IN ZNY CLASS E AIRSPACE.

Narrative

WE WERE ON THE MILTON 3 ARR GOING INTO LGA ARPT. THE CLRNC WAS TO CROSS VIBES AT 13000 FT. DURING THE DSCNT; I BRIEFED THE APCH AND TAXI RTE WITH MY FO; AND DID OTHER CHORES TO BE PREPARED FOR THE ARR INTO LGA. I WANTED TO GET THIS DONE BEFORE GETTING TO THE ZIG-ZAGGING COURSE THAT IS PART OF THE ARR AFTER XING ALLENTOWN VOR; SO THAT I WOULD NOT MISS ANY OF THE TURNS. OUR AIRPLANE DID NOT HAVE FMC; OR CDU EQUIP; SO THAT ON THE APCH ONE HAS TO BE VIGILANT TO TUNE THE RADIOS EARLY ENOUGH; SO AS NOT TO OVERSHOOT ONE OF THE MANY SHORT COURSE CHANGES. WE WERE TOLD BY AN EARLIER ATC FREQ TO KEEP OUR SPD UP FOR SPACING INTO LGA. I WAS GLAD TO OBLIGE; SINCE IT IS NOW A HASSLE TO GET INTO OR OUT OF LGA SINCE A COURT ORDER TO DO AWAY WITH SLOTS INTO LGA WAS MADE RECENTLY. UP AT ALT THE WINDS WERE OUT OF THE W AT 125 KTS; WHICH MEANT THAT OUR GND SPD DURING DSCNT WAS QUITE FAST. EVEN THOUGH THE TIME WAS SHORT DUE TO OUR GND SPD; I THOUGHT I HAD ACCOMPLISHED EVERYTHING REQUIRED FOR THE PREPARATIONS OF GOING INTO LGA. JUST AFTER ALLENTOWN VOR; ZNY ASKED IF WE WERE AT 13000 FT. I IMMEDIATELY REALIZED THAT I HAD FAILED TO SET THE ALTIMETER DSNDING THROUGH FL180; AND STILL HAD 29.92 INCHES IN THE WINDOW. THE ALTIMETER SETTING SHOULD HAVE BEEN 30.32 INCHES. THAT PLACED US 400 FT HIGH. I IMMEDIATELY RESET THE ALTIMETER AND DSNDED TO 13000 FT; AS AT THE SAME TIME ATC TOLD US TO DESCEND EXPEDITIOUSLY SINCE THERE WAS TFC AT 14000 FT. I WAS ANGRY WITH MYSELF THAT I HAD MISSED RESETTING THE ALTIMETER. HOWEVER; I WOULD PREFER THAT THIS ARR WAS A LITTLE STRAIGHTER.