Narrative:

During taxi out, sfo ground control changed taxi instructions 4 times. During some of these instructions, there were back taxi instructions on runway 28L, hold short instructions (of crossing runways and of the planned takeoff runway). Needless to say, confusion resulted at the hold short line of the planned departure runway (runway 28R). It seemed the captain was planning on moving into position and hold and the first officer said 'hold short, I think.' the captain stopped the aircraft and the first officer called the tower to confirm. The tower said hold short, we in the cockpit had a discussion that we may be over the hold short line (we couldn't tell from the perspective well above the runway). We as a crew decided that if it was in doubt that we were over the line that we needed to tell the tower. We did. Tower sent another aircraft around (that was on about a 4 mi final) and we were cleared into position and subsequent takeoff. The system worked as it should, the crew queried/advocated, the captain listened, and we all came up with a proper decision about the doubt issue and made the proper advisory call. Sfo ground needs to get their 'act' in one bag because of the relentless changes and distrs of continuously different changing taxi instructions. The real problem is that we may have been cleared into position and hold and it was bad instructions from the tower and/or ground. It might have been their mistake, who knows -- maybe, maybe not. The point is that the system of communication (CRM) and a partnership of working with ATC controllers to make the environment safer is the most important. Supplemental information from acn 616831: I believed the captain heard the clearance to hold short, however, he continued to taxi over the hold short line for runway 28R. I think he may have put the nose 8 ft beyond the line.

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Original NASA ASRS Text

Title: B747-400 CREW WAS GIVEN 4 CHANGES IN TAXI INSTRUCTION. THE CAPT TAXIED PAST THE RWY HOLD LINE IN THE CONFUSION.

Narrative: DURING TAXI OUT, SFO GND CTL CHANGED TAXI INSTRUCTIONS 4 TIMES. DURING SOME OF THESE INSTRUCTIONS, THERE WERE BACK TAXI INSTRUCTIONS ON RWY 28L, HOLD SHORT INSTRUCTIONS (OF XING RWYS AND OF THE PLANNED TKOF RWY). NEEDLESS TO SAY, CONFUSION RESULTED AT THE HOLD SHORT LINE OF THE PLANNED DEP RWY (RWY 28R). IT SEEMED THE CAPT WAS PLANNING ON MOVING INTO POS AND HOLD AND THE FO SAID 'HOLD SHORT, I THINK.' THE CAPT STOPPED THE ACFT AND THE FO CALLED THE TWR TO CONFIRM. THE TWR SAID HOLD SHORT, WE IN THE COCKPIT HAD A DISCUSSION THAT WE MAY BE OVER THE HOLD SHORT LINE (WE COULDN'T TELL FROM THE PERSPECTIVE WELL ABOVE THE RWY). WE AS A CREW DECIDED THAT IF IT WAS IN DOUBT THAT WE WERE OVER THE LINE THAT WE NEEDED TO TELL THE TWR. WE DID. TWR SENT ANOTHER ACFT AROUND (THAT WAS ON ABOUT A 4 MI FINAL) AND WE WERE CLRED INTO POS AND SUBSEQUENT TKOF. THE SYS WORKED AS IT SHOULD, THE CREW QUERIED/ADVOCATED, THE CAPT LISTENED, AND WE ALL CAME UP WITH A PROPER DECISION ABOUT THE DOUBT ISSUE AND MADE THE PROPER ADVISORY CALL. SFO GND NEEDS TO GET THEIR 'ACT' IN ONE BAG BECAUSE OF THE RELENTLESS CHANGES AND DISTRS OF CONTINUOUSLY DIFFERENT CHANGING TAXI INSTRUCTIONS. THE REAL PROB IS THAT WE MAY HAVE BEEN CLRED INTO POS AND HOLD AND IT WAS BAD INSTRUCTIONS FROM THE TWR AND/OR GND. IT MIGHT HAVE BEEN THEIR MISTAKE, WHO KNOWS -- MAYBE, MAYBE NOT. THE POINT IS THAT THE SYS OF COM (CRM) AND A PARTNERSHIP OF WORKING WITH ATC CTLRS TO MAKE THE ENVIRONMENT SAFER IS THE MOST IMPORTANT. SUPPLEMENTAL INFO FROM ACN 616831: I BELIEVED THE CAPT HEARD THE CLRNC TO HOLD SHORT, HOWEVER, HE CONTINUED TO TAXI OVER THE HOLD SHORT LINE FOR RWY 28R. I THINK HE MAY HAVE PUT THE NOSE 8 FT BEYOND THE LINE.

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.