Narrative:

While en route to farmingdale, ny, at FL410, we were given an amended clearance to fly direct to the psb VOR, then outbound on J-49 to intercept J70 to lvz VOR, then as filed. We were navigating with a global navigation system with GPS and VOR sensor inputs at the time. The amended clearance required the PNF to get out an en route chart to set up the necessary VOR radials to comply with the jet airway intercept point which was not a recognized intersection in the navigation box. Soon after receiving the amended clearance, ATC issued a crossing restr which both crew members understood to be, 'descend as to reach FL350 in the next 35 mi.' the PNF read back the clearance, dialed 35000 ft into the altitude preselect for the autoplt, and I began descending to meet the crossing restr. Passing through approximately 36400 ft, ATC issued a right 360 degree turn to re-intercept J-49 and informed us that our crossing restr assigned altitude had been FL370. I started an immediate right 360 degree turn, stopped the descent at 35800 ft and began a climb back to FL370. The PNF advised ATC that we understood our clearance had been to FL350, and that we were climbing back to FL370. ATC replied with 'roger' and no other comments were made to us. If the error was on our part, I believe the multiple tasks regarding our amended clearance and map research, shifting navaids followed rapidly by a crossing restr based on distance traveled rather than crossing a known fix, led to our confusion. Both pilots understood the altitude assigned was FL350, this may have been confused with the 35 mi crossing restr. Although I feel our clearance was to FL350, rather than FL370, I'm not 100% certain of it.

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Original NASA ASRS Text

Title: LTT ACFT IN CRUISE WAS GIVEN AMENDED CLRNC WHICH INCLUDED MULTIPLE LEGS. FLC HAD TO GET OUT CHARTS TO PROGRAM ACFT FOR CLRNC AS ATC ALSO GAVE DSCNT CLRNC TO DSND WITHIN THE NEXT 35 MI. FLC READ BACK AND SET NEWLY ASSIGNED ALT OF FL350, BUT AT 36400 FT, ATC INTERVENED TELLING THEM THE CLRNC WAS TO FL370.

Narrative: WHILE ENRTE TO FARMINGDALE, NY, AT FL410, WE WERE GIVEN AN AMENDED CLRNC TO FLY DIRECT TO THE PSB VOR, THEN OUTBOUND ON J-49 TO INTERCEPT J70 TO LVZ VOR, THEN AS FILED. WE WERE NAVING WITH A GLOBAL NAV SYS WITH GPS AND VOR SENSOR INPUTS AT THE TIME. THE AMENDED CLRNC REQUIRED THE PNF TO GET OUT AN ENRTE CHART TO SET UP THE NECESSARY VOR RADIALS TO COMPLY WITH THE JET AIRWAY INTERCEPT POINT WHICH WAS NOT A RECOGNIZED INTXN IN THE NAV BOX. SOON AFTER RECEIVING THE AMENDED CLRNC, ATC ISSUED A XING RESTR WHICH BOTH CREW MEMBERS UNDERSTOOD TO BE, 'DSND AS TO REACH FL350 IN THE NEXT 35 MI.' THE PNF READ BACK THE CLRNC, DIALED 35000 FT INTO THE ALT PRESELECT FOR THE AUTOPLT, AND I BEGAN DSNDING TO MEET THE XING RESTR. PASSING THROUGH APPROX 36400 FT, ATC ISSUED A R 360 DEG TURN TO RE-INTERCEPT J-49 AND INFORMED US THAT OUR XING RESTR ASSIGNED ALT HAD BEEN FL370. I STARTED AN IMMEDIATE R 360 DEG TURN, STOPPED THE DSCNT AT 35800 FT AND BEGAN A CLB BACK TO FL370. THE PNF ADVISED ATC THAT WE UNDERSTOOD OUR CLRNC HAD BEEN TO FL350, AND THAT WE WERE CLBING BACK TO FL370. ATC REPLIED WITH 'ROGER' AND NO OTHER COMMENTS WERE MADE TO US. IF THE ERROR WAS ON OUR PART, I BELIEVE THE MULTIPLE TASKS REGARDING OUR AMENDED CLRNC AND MAP RESEARCH, SHIFTING NAVAIDS FOLLOWED RAPIDLY BY A XING RESTR BASED ON DISTANCE TRAVELED RATHER THAN XING A KNOWN FIX, LED TO OUR CONFUSION. BOTH PLTS UNDERSTOOD THE ALT ASSIGNED WAS FL350, THIS MAY HAVE BEEN CONFUSED WITH THE 35 MI XING RESTR. ALTHOUGH I FEEL OUR CLRNC WAS TO FL350, RATHER THAN FL370, I'M NOT 100% CERTAIN OF IT.

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.