Narrative:

We thought approach clearance had been given and repeated by copilot. Started down from 3000 ft to 2500 ft crossing fix on approach. Relief pilot asked about clearance when approach gave the next aircraft 'intercept approach course.' controller asked us about our altitude and wanted us to return to 3000 ft. We did. Normal approach from then on. Supplemental information from acn 379916: the controller cleared us to intercept the approach course for runway 22L and I understood him to say intercept the approach for runway 22L. At approximately 2600 ft approach called and asked us if we were maintaining 3000 ft. I said no, that we had been cleared to intercept the approach, which I read back at the time of clearance. He restated that he had cleared us to intercept the approach course only and requested a climb to 3000 ft. I think fatigue was definitely a factor. The relief pilot said 'are you sure that was cleared for the approach?' I should have immediately taken that as a warning flag but did not as I was confident of the clearance and my readback. Next time I won't be so confident and will verify. I also wish the controller would have used some other phraseology. I'm not sure what, but something not quite so close. Hope this 'lessons learned' will help someone else!

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Original NASA ASRS Text

Title: A B767-300ER DSNDS FROM 3000 FT TO 2500 FT WITHOUT CLRNC. FLC THOUGHT THEY WERE CLRED TO A LOWER ALT.

Narrative: WE THOUGHT APCH CLRNC HAD BEEN GIVEN AND REPEATED BY COPLT. STARTED DOWN FROM 3000 FT TO 2500 FT XING FIX ON APCH. RELIEF PLT ASKED ABOUT CLRNC WHEN APCH GAVE THE NEXT ACFT 'INTERCEPT APCH COURSE.' CTLR ASKED US ABOUT OUR ALT AND WANTED US TO RETURN TO 3000 FT. WE DID. NORMAL APCH FROM THEN ON. SUPPLEMENTAL INFO FROM ACN 379916: THE CTLR CLRED US TO INTERCEPT THE APCH COURSE FOR RWY 22L AND I UNDERSTOOD HIM TO SAY INTERCEPT THE APCH FOR RWY 22L. AT APPROX 2600 FT APCH CALLED AND ASKED US IF WE WERE MAINTAINING 3000 FT. I SAID NO, THAT WE HAD BEEN CLRED TO INTERCEPT THE APCH, WHICH I READ BACK AT THE TIME OF CLRNC. HE RESTATED THAT HE HAD CLRED US TO INTERCEPT THE APCH COURSE ONLY AND REQUESTED A CLB TO 3000 FT. I THINK FATIGUE WAS DEFINITELY A FACTOR. THE RELIEF PLT SAID 'ARE YOU SURE THAT WAS CLRED FOR THE APCH?' I SHOULD HAVE IMMEDIATELY TAKEN THAT AS A WARNING FLAG BUT DID NOT AS I WAS CONFIDENT OF THE CLRNC AND MY READBACK. NEXT TIME I WON'T BE SO CONFIDENT AND WILL VERIFY. I ALSO WISH THE CTLR WOULD HAVE USED SOME OTHER PHRASEOLOGY. I'M NOT SURE WHAT, BUT SOMETHING NOT QUITE SO CLOSE. HOPE THIS 'LESSONS LEARNED' WILL HELP SOMEONE ELSE!

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.