Narrative:

Attached is a description of the event/situation as recorded in-flight just after it occurred. For clarification, 'howgozit' of our flight (item #1) is included. A NOTAM is item #2, and communications are items #3 through #5. The communications difficulties that our flight encountered were not so unusual for this location, and reception problems were resolved as the flight progressed eastbound. However, I believe that the NOTAM which tries to provide guidance to flcs for communication procedures is confusing. It refers to aircraft exiting ZOA fir. What's that? We were logged onto zak and, according to every chart we could find, talking to oakland. We were logged on to zak using cpdlc. We were not logged on to ZOA, and no member of the crew was aware of such an identify for oakland. While navigating in class 2 airspace air carrier X was communicating via cpdlc and was logged on to zak for ZOA. Estimate for pretty was YY16Z. Fir estimate was YY32Z. At +YY29 a message was received from 'ATC uplink' to contact czvr center on 133.4 MHZ. A response was sent at YY30Z. Several calls were made on 133.4 to establish contact and give progress with no response. A position report was made in the blind. About this time cpdlc message (ATC message) appeared something like 'ATC communication log-off' from oakland (zak). During this time an HF SELCAL from sfo commercial radio came in, and we were unable to establish voice contact due to poor HF communications quality. After switching to the secondary frequency we received a voice call (weak and barely readable) to contact vancouver on 135.2. We did so and upon call-up the center said 'radar contact, no position reports required.' about this time, or just after, an ACARS message was received at YY38Z 'ZOA requests air carrier X contact czvr center 135.2.' but in the meantime vancouver had switched us to another frequency. We then called vancouver center to inquire as to the need for a change to 135.2 and they told us to disregard. At YY47Z another ACARS message was received (and accepted) indicating that per NOTAM, we were required to contact commercial radio prior to exiting at ZOA fir. The NOTAM indicates datalink users are to contact commercial radio for VHF/HF frequency in next sector prior to exiting ZOA fir and gives several frequencys, including 135.2. Air carrier plotting chart indicates fir as 'oakland oceanic zak fir as does commercial chart pacific ocean and canada-alaska high altitude en route chart. We called ZSE to confirm the nomenclature of oakland fir. They indicated it is ZOA and anchorage is zak. Conflicting, or at least apparently confusing, verbiage along with an assignment of a frequency by the cpdlc and past experience of poor VHF communication approaching vancouver allowed the crew to believe they were communicating as ATC had directed. This is exacerbated by the relatively new use of cpdlc on an easterly routing in this area and the lack of responses to position reports from ATC when using this method. Callback conversation with reporter revealed the following information: reporter participated in fans structured callback program. Reporter had never heard of ZOA or even knew where the ZOA ADIZ was located. He only knew ZOA designation as zak. When the ZSE controller said zak was anchorage center, then the flight crew was confused. They were able to make radio contact, but not when they expected to. This is what caused them to ask questions of the controllers. It was never clear until analyst explained the designators in easy to understand terms.

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Original NASA ASRS Text

Title: A B747-400 FLC BECOMES CONFUSED OVER THE DESIGNATORS OF ZAK AND ZOA AND WHAT EACH REPRESENTS.

Narrative: ATTACHED IS A DESCRIPTION OF THE EVENT/SIT AS RECORDED INFLT JUST AFTER IT OCCURRED. FOR CLARIFICATION, 'HOWGOZIT' OF OUR FLT (ITEM #1) IS INCLUDED. A NOTAM IS ITEM #2, AND COMS ARE ITEMS #3 THROUGH #5. THE COMS DIFFICULTIES THAT OUR FLT ENCOUNTERED WERE NOT SO UNUSUAL FOR THIS LOCATION, AND RECEPTION PROBS WERE RESOLVED AS THE FLT PROGRESSED EBOUND. HOWEVER, I BELIEVE THAT THE NOTAM WHICH TRIES TO PROVIDE GUIDANCE TO FLCS FOR COM PROCS IS CONFUSING. IT REFERS TO ACFT EXITING ZOA FIR. WHAT'S THAT? WE WERE LOGGED ONTO ZAK AND, ACCORDING TO EVERY CHART WE COULD FIND, TALKING TO OAKLAND. WE WERE LOGGED ON TO ZAK USING CPDLC. WE WERE NOT LOGGED ON TO ZOA, AND NO MEMBER OF THE CREW WAS AWARE OF SUCH AN IDENT FOR OAKLAND. WHILE NAVING IN CLASS 2 AIRSPACE ACR X WAS COMMUNICATING VIA CPDLC AND WAS LOGGED ON TO ZAK FOR ZOA. ESTIMATE FOR PRETTY WAS YY16Z. FIR ESTIMATE WAS YY32Z. AT +YY29 A MESSAGE WAS RECEIVED FROM 'ATC UPLINK' TO CONTACT CZVR CTR ON 133.4 MHZ. A RESPONSE WAS SENT AT YY30Z. SEVERAL CALLS WERE MADE ON 133.4 TO ESTABLISH CONTACT AND GIVE PROGRESS WITH NO RESPONSE. A POS RPT WAS MADE IN THE BLIND. ABOUT THIS TIME CPDLC MESSAGE (ATC MESSAGE) APPEARED SOMETHING LIKE 'ATC COM LOG-OFF' FROM OAKLAND (ZAK). DURING THIS TIME AN HF SELCAL FROM SFO COMMERCIAL RADIO CAME IN, AND WE WERE UNABLE TO ESTABLISH VOICE CONTACT DUE TO POOR HF COMS QUALITY. AFTER SWITCHING TO THE SECONDARY FREQ WE RECEIVED A VOICE CALL (WEAK AND BARELY READABLE) TO CONTACT VANCOUVER ON 135.2. WE DID SO AND UPON CALL-UP THE CTR SAID 'RADAR CONTACT, NO POS RPTS REQUIRED.' ABOUT THIS TIME, OR JUST AFTER, AN ACARS MESSAGE WAS RECEIVED AT YY38Z 'ZOA REQUESTS ACR X CONTACT CZVR CTR 135.2.' BUT IN THE MEANTIME VANCOUVER HAD SWITCHED US TO ANOTHER FREQ. WE THEN CALLED VANCOUVER CTR TO INQUIRE AS TO THE NEED FOR A CHANGE TO 135.2 AND THEY TOLD US TO DISREGARD. AT YY47Z ANOTHER ACARS MESSAGE WAS RECEIVED (AND ACCEPTED) INDICATING THAT PER NOTAM, WE WERE REQUIRED TO CONTACT COMMERCIAL RADIO PRIOR TO EXITING AT ZOA FIR. THE NOTAM INDICATES DATALINK USERS ARE TO CONTACT COMMERCIAL RADIO FOR VHF/HF FREQ IN NEXT SECTOR PRIOR TO EXITING ZOA FIR AND GIVES SEVERAL FREQS, INCLUDING 135.2. ACR PLOTTING CHART INDICATES FIR AS 'OAKLAND OCEANIC ZAK FIR AS DOES COMMERCIAL CHART PACIFIC OCEAN AND CANADA-ALASKA HIGH ALT ENRTE CHART. WE CALLED ZSE TO CONFIRM THE NOMENCLATURE OF OAKLAND FIR. THEY INDICATED IT IS ZOA AND ANCHORAGE IS ZAK. CONFLICTING, OR AT LEAST APPARENTLY CONFUSING, VERBIAGE ALONG WITH AN ASSIGNMENT OF A FREQ BY THE CPDLC AND PAST EXPERIENCE OF POOR VHF COM APCHING VANCOUVER ALLOWED THE CREW TO BELIEVE THEY WERE COMMUNICATING AS ATC HAD DIRECTED. THIS IS EXACERBATED BY THE RELATIVELY NEW USE OF CPDLC ON AN EASTERLY ROUTING IN THIS AREA AND THE LACK OF RESPONSES TO POS RPTS FROM ATC WHEN USING THIS METHOD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR PARTICIPATED IN FANS STRUCTURED CALLBACK PROGRAM. RPTR HAD NEVER HEARD OF ZOA OR EVEN KNEW WHERE THE ZOA ADIZ WAS LOCATED. HE ONLY KNEW ZOA DESIGNATION AS ZAK. WHEN THE ZSE CTLR SAID ZAK WAS ANCHORAGE CTR, THEN THE FLC WAS CONFUSED. THEY WERE ABLE TO MAKE RADIO CONTACT, BUT NOT WHEN THEY EXPECTED TO. THIS IS WHAT CAUSED THEM TO ASK QUESTIONS OF THE CTLRS. IT WAS NEVER CLR UNTIL ANALYST EXPLAINED THE DESIGNATORS IN EASY TO UNDERSTAND TERMS.

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.