Narrative:

Taxiing out of MSL, the aircraft right main tires departed the prepared surface of the taxiway and sunk into the mud. Aircraft (DC9) weighed close to 100000 pounds at the time of the occurrence. There were 71 passenger on board and all passenger deplaned out the forward entrance stairs and returned to the terminal on foot. We arrived in MSL around XB30 and taxied into the ramp area on taxiway a. After our arrival, 3 other chartered B727's arrived and parked on the ramp so as to block our way back to taxiway a. The airfield diagram showed another taxiway (taxiway C) of equal width behind us and to our right (we were parked facing wbound). I radioed the FBO on the field and asked if they knew of any reason I shouldn't be able to use taxiway C to exit the ramp. They said 'no.' I paced off the 180 degree right turn out to the taxiway to include avoiding a C177 parked at our 2 O'clock position and a line of piper cherokees parked just to the north of the entrance to taxiway C. I had 2 wing walkers, one off my left wingtip and the other in front of the closest cherokee. As I swung the left wingtip past the last cherokee, approached the entrance to the taxiway, the main wheels departed the concrete and we came to an abrupt stop. Although the chart indicated txwys a and C being equal width, in reality, taxiway a was 75 ft wide and taxiway C was only 39 ft 10 inches wide. Additionally, the taxiway edge lights were a full 10 ft into the grass and the edge markings were completely obliterated. Neither the first officer nor myself could see where the concrete ended and the grass began. We only had the edge lights to go by.

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Original NASA ASRS Text

Title: A DC9 CREW TAXIES THEIR ACFT INTO THE MUD DURING A NIGHT OP. FLC CITES A PROB WITH THE TXWY C LIGHTS BEING LOCATED 10 FT OFF TO EITHER SIDE OF THE 39 FT 10 INCH WIDE TXWY AND NO TXWY WIDTH INFO INDICATED ON THE AERO CHART.

Narrative: TAXIING OUT OF MSL, THE ACFT R MAIN TIRES DEPARTED THE PREPARED SURFACE OF THE TXWY AND SUNK INTO THE MUD. ACFT (DC9) WEIGHED CLOSE TO 100000 LBS AT THE TIME OF THE OCCURRENCE. THERE WERE 71 PAX ON BOARD AND ALL PAX DEPLANED OUT THE FORWARD ENTRANCE STAIRS AND RETURNED TO THE TERMINAL ON FOOT. WE ARRIVED IN MSL AROUND XB30 AND TAXIED INTO THE RAMP AREA ON TXWY A. AFTER OUR ARR, 3 OTHER CHARTERED B727'S ARRIVED AND PARKED ON THE RAMP SO AS TO BLOCK OUR WAY BACK TO TXWY A. THE AIRFIELD DIAGRAM SHOWED ANOTHER TXWY (TXWY C) OF EQUAL WIDTH BEHIND US AND TO OUR R (WE WERE PARKED FACING WBOUND). I RADIOED THE FBO ON THE FIELD AND ASKED IF THEY KNEW OF ANY REASON I SHOULDN'T BE ABLE TO USE TXWY C TO EXIT THE RAMP. THEY SAID 'NO.' I PACED OFF THE 180 DEG R TURN OUT TO THE TXWY TO INCLUDE AVOIDING A C177 PARKED AT OUR 2 O'CLOCK POS AND A LINE OF PIPER CHEROKEES PARKED JUST TO THE N OF THE ENTRANCE TO TXWY C. I HAD 2 WING WALKERS, ONE OFF MY L WINGTIP AND THE OTHER IN FRONT OF THE CLOSEST CHEROKEE. AS I SWUNG THE L WINGTIP PAST THE LAST CHEROKEE, APCHED THE ENTRANCE TO THE TXWY, THE MAIN WHEELS DEPARTED THE CONCRETE AND WE CAME TO AN ABRUPT STOP. ALTHOUGH THE CHART INDICATED TXWYS A AND C BEING EQUAL WIDTH, IN REALITY, TXWY A WAS 75 FT WIDE AND TXWY C WAS ONLY 39 FT 10 INCHES WIDE. ADDITIONALLY, THE TXWY EDGE LIGHTS WERE A FULL 10 FT INTO THE GRASS AND THE EDGE MARKINGS WERE COMPLETELY OBLITERATED. NEITHER THE FO NOR MYSELF COULD SEE WHERE THE CONCRETE ENDED AND THE GRASS BEGAN. WE ONLY HAD THE EDGE LIGHTS TO GO BY.

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.