Narrative:

We were cruising at FL290 and were required to remain at that altitude due to a flight that was 5 mins behind us at FL310. Both aircraft were being controled by ZOA using the new fans datalink system. We were 3200 pounds behind our flight plan fuel forecast and because of air carrier reluctance to climb, I requested an off course climb to FL350, a more efficient altitude for us. The following clearance was received from ATC, 'cleared direct 1510N 150W, direct 12N 156W, direct 05N 164W, at 150W climb and maintain FL350, report reaching FL350.' we accepted the new clearance using the CDU prompt and the first officer built the new route in the CDU. We both checked and verified the new route and executed the change. We both somehow missed the 'at 150W' restr and began a climb to FL350 on the new heading. After reporting level at FL350 we received a message from ATC, 'your clearance was to climb at 150W, not before, verify altitude.' we were both surprised by this message and immediately began to reexamine the clearance and our actions. I sent the following message to ATC, 'now level FL350, estimate 150W 1025Z, misunderstood climb clearance'. A few mins later we were requested to maintain FL350 and we responded wilco. The following message was then received, 'possible pilot deviation, advise you contact ZOA.' we accepted that message and the flight continued to sydney. Fortunately due to the separation and divergent paths, a hazardous conflict did not occur with the flight. I feel several factors contributed to the error. Both the first officer and I had little actual experience using the fans since our original training in late 1995, and this was our first time seeing the ATC uplink clearance format. The new clearance was quickly accepted using the accept prompt, this action changed the screen to the verify response page, and diverted us from the print prompt which should have been selected before sending the accept message. If just the CDU screen is used to read the clearance, the critical work 'at' is in small font and very easy to overlook with dim screens and tired eyes. The correct operational procedure is to 'print and read aloud' and had we followed the procedure, the incident would not have occurred. Nearly 1 yr has elapsed since initial fans training and the present limited operations. This long period of time, without actual hands on experience and lacking some formal review, presents an opportunity for procedural errors. The procedure to 'print and read aloud' is critical in ensuring that all ATC clrncs are followed correctly. I feel that it should be repeatedly stressed in initial and annual proficiency training.

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Original NASA ASRS Text

Title: B747-400 FLC MISUNDERSTANDS CLRNC AND CLBS TO NEW ALT EARLY WHILE FLYING BTWN LAX AND SYD.

Narrative: WE WERE CRUISING AT FL290 AND WERE REQUIRED TO REMAIN AT THAT ALT DUE TO A FLT THAT WAS 5 MINS BEHIND US AT FL310. BOTH ACFT WERE BEING CTLED BY ZOA USING THE NEW FANS DATALINK SYS. WE WERE 3200 LBS BEHIND OUR FLT PLAN FUEL FORECAST AND BECAUSE OF ACR RELUCTANCE TO CLB, I REQUESTED AN OFF COURSE CLB TO FL350, A MORE EFFICIENT ALT FOR US. THE FOLLOWING CLRNC WAS RECEIVED FROM ATC, 'CLRED DIRECT 1510N 150W, DIRECT 12N 156W, DIRECT 05N 164W, AT 150W CLB AND MAINTAIN FL350, RPT REACHING FL350.' WE ACCEPTED THE NEW CLRNC USING THE CDU PROMPT AND THE FO BUILT THE NEW RTE IN THE CDU. WE BOTH CHKED AND VERIFIED THE NEW RTE AND EXECUTED THE CHANGE. WE BOTH SOMEHOW MISSED THE 'AT 150W' RESTR AND BEGAN A CLB TO FL350 ON THE NEW HEADING. AFTER RPTING LEVEL AT FL350 WE RECEIVED A MESSAGE FROM ATC, 'YOUR CLRNC WAS TO CLB AT 150W, NOT BEFORE, VERIFY ALT.' WE WERE BOTH SURPRISED BY THIS MESSAGE AND IMMEDIATELY BEGAN TO REEXAMINE THE CLRNC AND OUR ACTIONS. I SENT THE FOLLOWING MESSAGE TO ATC, 'NOW LEVEL FL350, ESTIMATE 150W 1025Z, MISUNDERSTOOD CLB CLRNC'. A FEW MINS LATER WE WERE REQUESTED TO MAINTAIN FL350 AND WE RESPONDED WILCO. THE FOLLOWING MESSAGE WAS THEN RECEIVED, 'POSSIBLE PLTDEV, ADVISE YOU CONTACT ZOA.' WE ACCEPTED THAT MESSAGE AND THE FLT CONTINUED TO SYDNEY. FORTUNATELY DUE TO THE SEPARATION AND DIVERGENT PATHS, A HAZARDOUS CONFLICT DID NOT OCCUR WITH THE FLT. I FEEL SEVERAL FACTORS CONTRIBUTED TO THE ERROR. BOTH THE FO AND I HAD LITTLE ACTUAL EXPERIENCE USING THE FANS SINCE OUR ORIGINAL TRAINING IN LATE 1995, AND THIS WAS OUR FIRST TIME SEEING THE ATC UPLINK CLRNC FORMAT. THE NEW CLRNC WAS QUICKLY ACCEPTED USING THE ACCEPT PROMPT, THIS ACTION CHANGED THE SCREEN TO THE VERIFY RESPONSE PAGE, AND DIVERTED US FROM THE PRINT PROMPT WHICH SHOULD HAVE BEEN SELECTED BEFORE SENDING THE ACCEPT MESSAGE. IF JUST THE CDU SCREEN IS USED TO READ THE CLRNC, THE CRITICAL WORK 'AT' IS IN SMALL FONT AND VERY EASY TO OVERLOOK WITH DIM SCREENS AND TIRED EYES. THE CORRECT OPERATIONAL PROC IS TO 'PRINT AND READ ALOUD' AND HAD WE FOLLOWED THE PROC, THE INCIDENT WOULD NOT HAVE OCCURRED. NEARLY 1 YR HAS ELAPSED SINCE INITIAL FANS TRAINING AND THE PRESENT LIMITED OPS. THIS LONG PERIOD OF TIME, WITHOUT ACTUAL HANDS ON EXPERIENCE AND LACKING SOME FORMAL REVIEW, PRESENTS AN OPPORTUNITY FOR PROCEDURAL ERRORS. THE PROC TO 'PRINT AND READ ALOUD' IS CRITICAL IN ENSURING THAT ALL ATC CLRNCS ARE FOLLOWED CORRECTLY. I FEEL THAT IT SHOULD BE REPEATEDLY STRESSED IN INITIAL AND ANNUAL PROFICIENCY TRAINING.

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.