Narrative:

Wbound at FL310 with reports of bumpy air ahead, we requested lower. Controller gave us FL260. Passing FL275 controller said, 'say your altitude.' I responded FL273. He said you were assigned FL280. Traffic eastbound at FL270. We had the traffic in sight and wrongfully assumed we had sufficient lateral clearance. We passed about 3 mi laterally. 2 frequencys later, we were given a phone number to call at ZAB. When on the ground, I called number at ZAB and after a review of the tapes I was told it was a controller error. This was the last leg of 5 flying days and I feel maybe I should have questioned the controller instead of 'assuming' we had lateral separation. It seems that I always read of incidents happening on the last leg of a sequence.

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Original NASA ASRS Text

Title: AN ACR MLG WAS CLRED TO DSND TO FL260. PASSING FL273 THE ARTCC CTLR QUESTIONED THE MLG ALT AND GAVE HIM TFC AT FL270 AND SAID THAT HE HAD ONLY CLRED THE MLG TO FL280. LATER DURING FLC ATC REVIEW, IT WAS DETERMINED TO BE A SYS ERROR.

Narrative: WBOUND AT FL310 WITH RPTS OF BUMPY AIR AHEAD, WE REQUESTED LOWER. CTLR GAVE US FL260. PASSING FL275 CTLR SAID, 'SAY YOUR ALT.' I RESPONDED FL273. HE SAID YOU WERE ASSIGNED FL280. TFC EBOUND AT FL270. WE HAD THE TFC IN SIGHT AND WRONGFULLY ASSUMED WE HAD SUFFICIENT LATERAL CLRNC. WE PASSED ABOUT 3 MI LATERALLY. 2 FREQS LATER, WE WERE GIVEN A PHONE NUMBER TO CALL AT ZAB. WHEN ON THE GND, I CALLED NUMBER AT ZAB AND AFTER A REVIEW OF THE TAPES I WAS TOLD IT WAS A CTLR ERROR. THIS WAS THE LAST LEG OF 5 FLYING DAYS AND I FEEL MAYBE I SHOULD HAVE QUESTIONED THE CTLR INSTEAD OF 'ASSUMING' WE HAD LATERAL SEPARATION. IT SEEMS THAT I ALWAYS READ OF INCIDENTS HAPPENING ON THE LAST LEG OF A SEQUENCE.

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.