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Altitude excursion over the pacific when clearance to cross and maintain was misinterped as a clearance within a previously issued block altitude clearance.
| Attributes | |
| ACN | 492558 |
| Time | |
| Date | 200011 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | intersection : canol |
| State Reference | FO |
| Altitude | msl bound lower : 34000 msl bound upper : 35000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B747-400 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : enroute altitude change |
| Route In Use | enroute : pacific enroute airway : b577.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 219 flight time total : 19000 flight time type : 3800 |
| ASRS Report | 492558 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| ASRS Report | 492556 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure |
| Independent Detector | other controllerb |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were cleared by akl ATC to maintain block altitude FL330-FL350. Shortly after switching to ZOA, they cleared us to cross 150W at and maintain FL340. We followed SOP in printing and confirming the clearance and climbed to FL340. The relief pilots then took over. I briefed them we were in a block altitude FL330-FL350 and had complied with the crossing restr. Subsequently, they climbed to FL350 in accordance with my briefing that we were in the FL330-FL350 block. I missed the maintain FL340 part of the clearance. Please call for more details. If cancel block had been included in the clearance as is usually the case, the incident would not have happened.
Original NASA ASRS Text
Title: ALT EXCURSION OVER THE PACIFIC WHEN CLRNC TO CROSS AND MAINTAIN WAS MISINTERPED AS A CLRNC WITHIN A PREVIOUSLY ISSUED BLOCK ALT CLRNC.
Narrative: WE WERE CLRED BY AKL ATC TO MAINTAIN BLOCK ALT FL330-FL350. SHORTLY AFTER SWITCHING TO ZOA, THEY CLRED US TO CROSS 150W AT AND MAINTAIN FL340. WE FOLLOWED SOP IN PRINTING AND CONFIRMING THE CLRNC AND CLBED TO FL340. THE RELIEF PLTS THEN TOOK OVER. I BRIEFED THEM WE WERE IN A BLOCK ALT FL330-FL350 AND HAD COMPLIED WITH THE XING RESTR. SUBSEQUENTLY, THEY CLBED TO FL350 IN ACCORDANCE WITH MY BRIEFING THAT WE WERE IN THE FL330-FL350 BLOCK. I MISSED THE MAINTAIN FL340 PART OF THE CLRNC. PLEASE CALL FOR MORE DETAILS. IF CANCEL BLOCK HAD BEEN INCLUDED IN THE CLRNC AS IS USUALLY THE CASE, THE INCIDENT WOULD NOT HAVE HAPPENED.
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.