Narrative:

We were on the milton 3 arrival going into lga airport. The clearance was to cross vibes at 13000 ft. During the descent, I briefed the approach and taxi route with my first officer, and did other chores to be prepared for the arrival into lga. I wanted to get this done before getting to the zig-zagging course that is part of the arrival after crossing allentown VOR, so that I would not miss any of the turns. Our airplane did not have FMC, or CDU equipment, so that on the approach 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 frequency to keep our speed 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 altitude the winds were out of the west at 125 KTS, which meant that our ground speed during descent was quite fast. Even though the time was short due to our ground speed, 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 descending 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 descended to 13000 ft, as at the same time ATC told us to descend expeditiously since there was traffic at 14000 ft. I was angry with myself that I had missed resetting the altimeter. However, I would prefer that this arrival was a little straighter.

Google
 

Original NASA ASRS Text

Title: 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.

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.