Narrative:

I was the first officer during this incident and was operating the radio. Our flight plan included the nanci 5 arrival into lga. While in radar and radio contact with ZDC, we received clearance to cross kerno intersection at FL260. I read back the clearance, set FL260 in altitude window and captain verbally acknowledged. After setting the restr in the FMC, the captain began his descent and we called center out of FL370. Center called back asking why we were descending and how long ago we received the clearance. The captain disconnected the autoplt and stopped the descent at FL360. We then told controller that we had been cleared to cross kerno at FL260 3 mins ago on this frequency. Controller then gave us an off course heading to 010 degrees and immediate descent to FL260. Captain and I are both confident that we heard, read back, and verified the proper clearance. Supplemental information from acn 325264: established at FL370 on the nanci 5 arrival into new york's lga airport, ZDC gave us clearance to cross kerno intersection at FL260. The first officer was working the radios and read back the entire clearance. He then reset the altitude capture to FL260 and I verbally confirmed FL260 was set. I then rechked the FMC to confirm it was programmed for kerno at FL260. About 3 mins after receiving the clearance I started out of FL370 and we called 'leaving FL370.' ZDC responded with 'maintain FL370.' the aircraft had already begun an autoplt descent so I disconnected the autoplt and abruptly stopped the descent at FL366 and returned to FL370. He then cleared us to turn left heading 010 degrees, descend to FL260, expedite the descent and we complied. Through about FL330 we were cleared back direct kerno intersection. We do not know if a conflict existed. At the time we were not advised of one. I believe the only problem to be a miscom on the part of ZDC.

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Original NASA ASRS Text

Title: AFTER FLC READ BACK CLRNC, SET THE NEW ALT CAPTURE TO FL260 WITH CONFIRMATION BY CAPT, RPTR CAPT COMMENCED DSCNT TO CROSS KERNO AT FL260, AS CLRED. FLC CALLED LEAVING FL370 AND CTR RESPONDED WITH, MAINTAIN FL370, ASKED WHAT THE ALT CLRNC WAS AND WHEN WAS THAT CLRNC RECEIVED. CTLR THEN VECTORED ACFT AND EXPEDITED THEIR DSCNT.

Narrative: I WAS THE FO DURING THIS INCIDENT AND WAS OPERATING THE RADIO. OUR FLT PLAN INCLUDED THE NANCI 5 ARR INTO LGA. WHILE IN RADAR AND RADIO CONTACT WITH ZDC, WE RECEIVED CLRNC TO CROSS KERNO INTXN AT FL260. I READ BACK THE CLRNC, SET FL260 IN ALT WINDOW AND CAPT VERBALLY ACKNOWLEDGED. AFTER SETTING THE RESTR IN THE FMC, THE CAPT BEGAN HIS DSCNT AND WE CALLED CTR OUT OF FL370. CTR CALLED BACK ASKING WHY WE WERE DSNDING AND HOW LONG AGO WE RECEIVED THE CLRNC. THE CAPT DISCONNECTED THE AUTOPLT AND STOPPED THE DSCNT AT FL360. WE THEN TOLD CTLR THAT WE HAD BEEN CLRED TO CROSS KERNO AT FL260 3 MINS AGO ON THIS FREQ. CTLR THEN GAVE US AN OFF COURSE HDG TO 010 DEGS AND IMMEDIATE DSCNT TO FL260. CAPT AND I ARE BOTH CONFIDENT THAT WE HEARD, READ BACK, AND VERIFIED THE PROPER CLRNC. SUPPLEMENTAL INFO FROM ACN 325264: ESTABLISHED AT FL370 ON THE NANCI 5 ARR INTO NEW YORK'S LGA ARPT, ZDC GAVE US CLRNC TO CROSS KERNO INTXN AT FL260. THE FO WAS WORKING THE RADIOS AND READ BACK THE ENTIRE CLRNC. HE THEN RESET THE ALT CAPTURE TO FL260 AND I VERBALLY CONFIRMED FL260 WAS SET. I THEN RECHKED THE FMC TO CONFIRM IT WAS PROGRAMMED FOR KERNO AT FL260. ABOUT 3 MINS AFTER RECEIVING THE CLRNC I STARTED OUT OF FL370 AND WE CALLED 'LEAVING FL370.' ZDC RESPONDED WITH 'MAINTAIN FL370.' THE ACFT HAD ALREADY BEGUN AN AUTOPLT DSCNT SO I DISCONNECTED THE AUTOPLT AND ABRUPTLY STOPPED THE DSCNT AT FL366 AND RETURNED TO FL370. HE THEN CLRED US TO TURN L HDG 010 DEGS, DSND TO FL260, EXPEDITE THE DSCNT AND WE COMPLIED. THROUGH ABOUT FL330 WE WERE CLRED BACK DIRECT KERNO INTXN. WE DO NOT KNOW IF A CONFLICT EXISTED. AT THE TIME WE WERE NOT ADVISED OF ONE. I BELIEVE THE ONLY PROB TO BE A MISCOM ON THE PART OF ZDC.

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.