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A B747 flight crew received a clearance in pacific oceanic airspace which omitted a required navigation fix.
| Attributes | |
| ACN | 447950 |
| Time | |
| Date | 199909 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : zoa.artcc |
| State Reference | CA |
| Altitude | msl single value : 35000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dawn |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B747 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Route In Use | enroute : pacific |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 100 flight time total : 15000 flight time type : 1000 |
| ASRS Report | 447950 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer pilot : instrument pilot : multi engine |
| Experience | flight time last 90 days : 100 flight time total : 7000 flight time type : 500 |
| ASRS Report | 448561 |
| Events | |
| Anomaly | non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact none taken : anomaly accepted |
| Supplementary | |
| Problem Areas | ATC Human Performance Environmental Factor |
| Primary Problem | Ambiguous |
Narrative:
SELCAL from sfo commercial radio. They stated 'ATC clears air carrier X to 50N 131W, 49N 121W, tou.' I read back exactly that to commercial radio. Prior to that, we were going to ornai. We thought that clearance meant to proceed direct to 50N 131W, which we did. Approximately 15 mins later we checked in with vancouver center with position report. He asked our clearance, which we read back to him. He indicated we were cleared that route 'after' ornai. Controller stated there was no traffic conflict or separation problems, so there was no problem with him. We proceeded on with no further problems. Supplemental information from acn 448561: the radio was very broken and we asked that the clearance be repeated. We repeated the clearance back and asked for confirmation. They said 'roger.' the culprit here was the extremely poor HF connection.
Original NASA ASRS Text
Title: A B747 FLC RECEIVED A CLRNC IN PACIFIC OCEANIC AIRSPACE WHICH OMITTED A REQUIRED NAV FIX.
Narrative: SELCAL FROM SFO COMMERCIAL RADIO. THEY STATED 'ATC CLRS ACR X TO 50N 131W, 49N 121W, TOU.' I READ BACK EXACTLY THAT TO COMMERCIAL RADIO. PRIOR TO THAT, WE WERE GOING TO ORNAI. WE THOUGHT THAT CLRNC MEANT TO PROCEED DIRECT TO 50N 131W, WHICH WE DID. APPROX 15 MINS LATER WE CHKED IN WITH VANCOUVER CTR WITH POS RPT. HE ASKED OUR CLRNC, WHICH WE READ BACK TO HIM. HE INDICATED WE WERE CLRED THAT RTE 'AFTER' ORNAI. CTLR STATED THERE WAS NO TFC CONFLICT OR SEPARATION PROBS, SO THERE WAS NO PROB WITH HIM. WE PROCEEDED ON WITH NO FURTHER PROBS. SUPPLEMENTAL INFO FROM ACN 448561: THE RADIO WAS VERY BROKEN AND WE ASKED THAT THE CLRNC BE REPEATED. WE REPEATED THE CLRNC BACK AND ASKED FOR CONFIRMATION. THEY SAID 'ROGER.' THE CULPRIT HERE WAS THE EXTREMELY POOR HF CONNECTION.
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.