Narrative:

My purpose is to highlight the close taxi environment at the approach end of sfo runway 1R, and recommend an appropriate note be added to the sfo airport diagram. I was captain of air carrier X, a B777-200. We were instructed by sfo ground control to follow a B747-400 on taxiway a to sfo runway 1R. Nearing the approach end of runway 1R we switched to sfo tower (120.5). The B747 was stopped on taxiway a, on the centerline, 10-20 ft short of the hold short line for runway 1R. I was on taxiway a about 200 yards behind air carrier Y when sfo tower instructed me to pass air carrier Y on taxiway A1, if sufficient lateral wingtip clearance existed. I had my first officer check the sfo airport chart and verify that no notes prohibited 2 widebody transport's from passing on the subject txwys. Using the published cockpit visual references, it appeared that the spacing was adequate to pass safely. I elected to taxi slowly to allow me to stop if necessary. During the passing maneuver, I used the published cockpit visual references to monitor the ground track of my left wingtip (I cannot see my wingtips from the B777 captain's seat). In addition, I positioned the nosewheel about 3 ft to the right of taxiway A1 centerline to ensure maximum wingtip clearance. I passed air carrier Y uneventfully and completed the takeoff from runway 1R. About 1 hour after takeoff, a company B747 fleet technical captain, deadheading in the main cabin passed me a note. The captain's note stated that 'it appeared to him that my left wingtip had passed over the top of the right winglet on air carrier Y while we were taxiing' but that no contact had occurred. I then spoke with him and verified that no contact had occurred. I informed him that from our cockpit references it appeared that lateral wingtip separation existed. After arrival my first officer and I performed a visual inspection of the left wingtip and observed no damage. In addition I had dispatch send an ACARS message to air carrier Y asking if they had observed the clearance of my wingtip when I passed them on taxiway A1 in sfo. The crew of air carrier X said that the overall spacing between the 2 airplanes looked ok to them, but that they did not observe the specific clearance distance as my wingtip passed near their right winglet.

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Original NASA ASRS Text

Title: A B777 WING PASSES OVER A B747'S WINGLET ACCORDING TO AN ACR CAPT RIDING IN THE CABIN AS THE B777 ON TXWY A1 PASSED BY A B747 HOLDING ON TXWY A NEAR THE APCH END OF RWY 1R AT SFO.

Narrative: MY PURPOSE IS TO HIGHLIGHT THE CLOSE TAXI ENVIRONMENT AT THE APCH END OF SFO RWY 1R, AND RECOMMEND AN APPROPRIATE NOTE BE ADDED TO THE SFO ARPT DIAGRAM. I WAS CAPT OF ACR X, A B777-200. WE WERE INSTRUCTED BY SFO GND CTL TO FOLLOW A B747-400 ON TXWY A TO SFO RWY 1R. NEARING THE APCH END OF RWY 1R WE SWITCHED TO SFO TWR (120.5). THE B747 WAS STOPPED ON TXWY A, ON THE CTRLINE, 10-20 FT SHORT OF THE HOLD SHORT LINE FOR RWY 1R. I WAS ON TXWY A ABOUT 200 YARDS BEHIND ACR Y WHEN SFO TWR INSTRUCTED ME TO PASS ACR Y ON TXWY A1, IF SUFFICIENT LATERAL WINGTIP CLRNC EXISTED. I HAD MY FO CHK THE SFO ARPT CHART AND VERIFY THAT NO NOTES PROHIBITED 2 WDB'S FROM PASSING ON THE SUBJECT TXWYS. USING THE PUBLISHED COCKPIT VISUAL REFS, IT APPEARED THAT THE SPACING WAS ADEQUATE TO PASS SAFELY. I ELECTED TO TAXI SLOWLY TO ALLOW ME TO STOP IF NECESSARY. DURING THE PASSING MANEUVER, I USED THE PUBLISHED COCKPIT VISUAL REFS TO MONITOR THE GND TRACK OF MY L WINGTIP (I CANNOT SEE MY WINGTIPS FROM THE B777 CAPT'S SEAT). IN ADDITION, I POSITIONED THE NOSEWHEEL ABOUT 3 FT TO THE R OF TXWY A1 CTRLINE TO ENSURE MAX WINGTIP CLRNC. I PASSED ACR Y UNEVENTFULLY AND COMPLETED THE TKOF FROM RWY 1R. ABOUT 1 HR AFTER TKOF, A COMPANY B747 FLEET TECHNICAL CAPT, DEADHEADING IN THE MAIN CABIN PASSED ME A NOTE. THE CAPT'S NOTE STATED THAT 'IT APPEARED TO HIM THAT MY L WINGTIP HAD PASSED OVER THE TOP OF THE R WINGLET ON ACR Y WHILE WE WERE TAXIING' BUT THAT NO CONTACT HAD OCCURRED. I THEN SPOKE WITH HIM AND VERIFIED THAT NO CONTACT HAD OCCURRED. I INFORMED HIM THAT FROM OUR COCKPIT REFS IT APPEARED THAT LATERAL WINGTIP SEPARATION EXISTED. AFTER ARR MY FO AND I PERFORMED A VISUAL INSPECTION OF THE L WINGTIP AND OBSERVED NO DAMAGE. IN ADDITION I HAD DISPATCH SEND AN ACARS MESSAGE TO ACR Y ASKING IF THEY HAD OBSERVED THE CLRNC OF MY WINGTIP WHEN I PASSED THEM ON TXWY A1 IN SFO. THE CREW OF ACR X SAID THAT THE OVERALL SPACING BTWN THE 2 AIRPLANES LOOKED OK TO THEM, BUT THAT THEY DID NOT OBSERVE THE SPECIFIC CLRNC DISTANCE AS MY WINGTIP PASSED NEAR THEIR R WINGLET.

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.