Narrative:

I have been flying the west and south pacific intermittently since 1972. My understanding was that tracks west and south of hawaii are separated by a minimum of 100 mi and 20 mins. In trail, my flight from auckland, new zealand to hnl was relatively uneventful and smooth until crossing the equator. We encountered a number of small cumulus buildups and stratus layers and deviated for the sake of passenger comfort. We were 3 mins late at the next fix (which is legal), and I advised the first officer to add 5 mins to his next estimate because there was considerable return on the radar on the 300 mi scale. Before reaching the next fix, arinc requested a verification of the estimate, which we did. We hit the fix 1 min early. Some time later (about 5 mins before being handed off to ZHU) we were selcaled and told to descend to 35000'. ZHU, when I questioned them, advised that another carrier was on our track behind us and that minimum sep was being diminished. This is the first we knew of the following aircraft. We had been given a .83 mach speed at the equator, the following aircraft an .84. I was requested to call oceanic control after landing. The supervisor wanted to know how I'd lost 50 KTS ground speed on those 2 legs in question (about 600 mi). I informed him that I had deviated left and right of track about 25 mi several times. He told me that I must inform oceanic control of any deviation. Frankly, given the transmission problems on high frequency in that area, this is often difficult and too late to be of any help. Obviously the following aircraft did not deviate and began overtaking us. I will pointout that I hit my estimates in a timely manner, and according to the supervisor sep was never compromised.

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Original NASA ASRS Text

Title: ACR WDB TRACK HEADING DEVIATION AVOIDING TSTM ACTIVITY ON EXTENDED OVERWATER OPERATION. FAILED TO NOTIFY ARTCC.

Narrative: I HAVE BEEN FLYING THE W AND S PACIFIC INTERMITTENTLY SINCE 1972. MY UNDERSTANDING WAS THAT TRACKS W AND S OF HAWAII ARE SEPARATED BY A MINIMUM OF 100 MI AND 20 MINS. IN TRAIL, MY FLT FROM AUCKLAND, NEW ZEALAND TO HNL WAS RELATIVELY UNEVENTFUL AND SMOOTH UNTIL XING THE EQUATOR. WE ENCOUNTERED A NUMBER OF SMALL CUMULUS BUILDUPS AND STRATUS LAYERS AND DEVIATED FOR THE SAKE OF PAX COMFORT. WE WERE 3 MINS LATE AT THE NEXT FIX (WHICH IS LEGAL), AND I ADVISED THE F/O TO ADD 5 MINS TO HIS NEXT ESTIMATE BECAUSE THERE WAS CONSIDERABLE RETURN ON THE RADAR ON THE 300 MI SCALE. BEFORE REACHING THE NEXT FIX, ARINC REQUESTED A VERIFICATION OF THE ESTIMATE, WHICH WE DID. WE HIT THE FIX 1 MIN EARLY. SOME TIME LATER (ABOUT 5 MINS BEFORE BEING HANDED OFF TO ZHU) WE WERE SELCALED AND TOLD TO DSND TO 35000'. ZHU, WHEN I QUESTIONED THEM, ADVISED THAT ANOTHER CARRIER WAS ON OUR TRACK BEHIND US AND THAT MINIMUM SEP WAS BEING DIMINISHED. THIS IS THE FIRST WE KNEW OF THE FOLLOWING ACFT. WE HAD BEEN GIVEN A .83 MACH SPD AT THE EQUATOR, THE FOLLOWING ACFT AN .84. I WAS REQUESTED TO CALL OCEANIC CTL AFTER LNDG. THE SUPVR WANTED TO KNOW HOW I'D LOST 50 KTS GND SPD ON THOSE 2 LEGS IN QUESTION (ABOUT 600 MI). I INFORMED HIM THAT I HAD DEVIATED LEFT AND RIGHT OF TRACK ABOUT 25 MI SEVERAL TIMES. HE TOLD ME THAT I MUST INFORM OCEANIC CTL OF ANY DEVIATION. FRANKLY, GIVEN THE XMISSION PROBS ON HIGH FREQ IN THAT AREA, THIS IS OFTEN DIFFICULT AND TOO LATE TO BE OF ANY HELP. OBVIOUSLY THE FOLLOWING ACFT DID NOT DEVIATE AND BEGAN OVERTAKING US. I WILL POINTOUT THAT I HIT MY ESTIMATES IN A TIMELY MANNER, AND ACCORDING TO THE SUPVR SEP WAS NEVER COMPROMISED.

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.