Narrative:

We were departing sdf for ont at XA00 local. We were cleared to taxi to runway 19 via taxiway D, north to taxiway G, west to taxiway P, and north to runway 19. When turning north from taxiway G onto taxiway P, the aircraft slowed and listed slightly to the right. We advised ground control that we had a problem and may have left the taxiway. An aircraft behind us confirmed that the right main gear was off the taxiway. None of the crew realized that we were even close to the edge. At the time the checklist had been completed and the engines were all started, there were no distrs. After exiting the aircraft and inspecting the tracks, we saw another set of aircraft tracks that were off farther than ours. It is my belief that the yellow taxi line at this intersection indicates a more shallow turn than that actually required, and that lulled me into following the line father than going beyond it as is required to negotiate a successful turn in a long aircraft.

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Original NASA ASRS Text

Title: DC8 CARGOLINER TAXIING FOR TKOF, CUT A CORNER. THE R MAIN GEAR DEPARTED THE TXWY AND THE ACFT WAS STUCK IN THE MUD. CAPT STATED HE FOLLOWED THE YELLOW LINE RATHER THAN GOING BEYOND IT AS REQUIRED FOR LONG ACFT.

Narrative: WE WERE DEPARTING SDF FOR ONT AT XA00 LCL. WE WERE CLRED TO TAXI TO RWY 19 VIA TXWY D, N TO TXWY G, W TO TXWY P, AND N TO RWY 19. WHEN TURNING N FROM TXWY G ONTO TXWY P, THE ACFT SLOWED AND LISTED SLIGHTLY TO THE R. WE ADVISED GND CTL THAT WE HAD A PROB AND MAY HAVE LEFT THE TXWY. AN ACFT BEHIND US CONFIRMED THAT THE R MAIN GEAR WAS OFF THE TXWY. NONE OF THE CREW REALIZED THAT WE WERE EVEN CLOSE TO THE EDGE. AT THE TIME THE CHKLIST HAD BEEN COMPLETED AND THE ENGS WERE ALL STARTED, THERE WERE NO DISTRS. AFTER EXITING THE ACFT AND INSPECTING THE TRACKS, WE SAW ANOTHER SET OF ACFT TRACKS THAT WERE OFF FARTHER THAN OURS. IT IS MY BELIEF THAT THE YELLOW TAXI LINE AT THIS INTXN INDICATES A MORE SHALLOW TURN THAN THAT ACTUALLY REQUIRED, AND THAT LULLED ME INTO FOLLOWING THE LINE FATHER THAN GOING BEYOND IT AS IS REQUIRED TO NEGOTIATE A SUCCESSFUL TURN IN A LONG ACFT.

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.