Narrative:

On 747 flight wbound between nuluk and ninna on R220 at FL350. Due to what appeared to be an impending shutdown of #4 engine due to excessive oil consumption, we decided to get a rerte back on R220 to anchorage since fuel consumption on 3 engines made a continuance to narita unacceptable and diversion airports along the route were much less suitable than anchorage. We did not declare an emergency because we had not shut down #4 engine yet. We requested a rerte from zan via VHF. Zan informed us that we could not reverse course at FL350 due to traffic and could not descend on track, then reverse course due to traffic. We suggested a deviation south of track, but that would put us in conflict with traffic on R220 and the next route south. We had converging traffic (air carrier B 747) on 517 converting into R220 at ninna. We asked zan, other than continuing wbound on R220, what would he suggest. He suggested deviate right, then descend, then reverse direction. I made a 45 degree right turn rather than 90 degrees so as to stay ahead of air carrier B. I had visual contact and air carrier B confirmed visual contact after being informed by center of our intentions. Starting the descent, I noticed air carrier B gaining on us via visual and TCASII. I shallowed the deviation to 30 degrees to stay ahead. We passed through air carrier B's altitude of FL310 at over 5 mi separation on TCASII but that is not the parameters for traffic separation on the nopal. Air carrier B appeared to make a left turn to increase separation. There were no TA's or RA's from the TCASII. Once established at FL290, we continued the right turn and reestablished eastbound on R220 to anchorage. TCASII was an invaluable tool to back up the visual separation.

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Original NASA ASRS Text

Title: HIGH ENG OIL CONSUMPTION CAUSES AN ACR WDB TO DIVERT LAND.

Narrative: ON 747 FLT WBOUND BTWN NULUK AND NINNA ON R220 AT FL350. DUE TO WHAT APPEARED TO BE AN IMPENDING SHUTDOWN OF #4 ENG DUE TO EXCESSIVE OIL CONSUMPTION, WE DECIDED TO GET A RERTE BACK ON R220 TO ANCHORAGE SINCE FUEL CONSUMPTION ON 3 ENGS MADE A CONTINUANCE TO NARITA UNACCEPTABLE AND DIVERSION ARPTS ALONG THE RTE WERE MUCH LESS SUITABLE THAN ANCHORAGE. WE DID NOT DECLARE AN EMER BECAUSE WE HAD NOT SHUT DOWN #4 ENG YET. WE REQUESTED A RERTE FROM ZAN VIA VHF. ZAN INFORMED US THAT WE COULD NOT REVERSE COURSE AT FL350 DUE TO TFC AND COULD NOT DSND ON TRACK, THEN REVERSE COURSE DUE TO TFC. WE SUGGESTED A DEV S OF TRACK, BUT THAT WOULD PUT US IN CONFLICT WITH TFC ON R220 AND THE NEXT RTE S. WE HAD CONVERGING TFC (ACR B 747) ON 517 CONVERTING INTO R220 AT NINNA. WE ASKED ZAN, OTHER THAN CONTINUING WBOUND ON R220, WHAT WOULD HE SUGGEST. HE SUGGESTED DEVIATE R, THEN DSND, THEN REVERSE DIRECTION. I MADE A 45 DEG R TURN RATHER THAN 90 DEGS SO AS TO STAY AHEAD OF ACR B. I HAD VISUAL CONTACT AND ACR B CONFIRMED VISUAL CONTACT AFTER BEING INFORMED BY CTR OF OUR INTENTIONS. STARTING THE DSCNT, I NOTICED ACR B GAINING ON US VIA VISUAL AND TCASII. I SHALLOWED THE DEV TO 30 DEGS TO STAY AHEAD. WE PASSED THROUGH ACR B'S ALT OF FL310 AT OVER 5 MI SEPARATION ON TCASII BUT THAT IS NOT THE PARAMETERS FOR TFC SEPARATION ON THE NOPAL. ACR B APPEARED TO MAKE A L TURN TO INCREASE SEPARATION. THERE WERE NO TA'S OR RA'S FROM THE TCASII. ONCE ESTABLISHED AT FL290, WE CONTINUED THE R TURN AND REESTABLISHED EBOUND ON R220 TO ANCHORAGE. TCASII WAS AN INVALUABLE TOOL TO BACK UP THE VISUAL SEPARATION.

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.