Narrative:

At about XA00 on aug/xa/98, we pushed back out of gate xx at las and were directed by ramp tower to taxi to spot 4. While taxiing out of the ramp, we were extra vigilant due to the fact that our NOTAMS had highlighted 2 hazards in the area: 1) 2 light poles in the center of the ramp, and 2) a ditch in the area. Prior to leaving the gate, I recall asking the captain if he knew where this ditch was and he stated that he did not. The NOTAM only said something to this effect: caution -- there is a ditch located directly in front of the terminal and it is very difficult to see. It gave no indication where in front on the terminal it was, and seemed to imply that it was close to the terminal. Just prior to pushback, I copied the new ATIS and told the others that the winds were now being reported as 130 degrees at 6 KTS, but the duty runway was still runway 25R. Due to our weight and the high outside air temperature, we would probably not be able to use runway 25R with that tailwind. As we got to spot 4, I asked the ground controller what the current winds were and she said that they were 130 degrees at 5 KTS. I asked her to standby while we checked our performance data. While the so did that, the captain and I switched from our ramp diagram (company chart) to the airport diagram. The so then informed us that we would need runway 7L or runway 7R, preferably runway 7L. I passed that on to the ground controller and she gave us our taxi instructions. Initially, she said to turn left on taxiway C, right on taxiway C5, right on taxiway B, and hold short of runway 19L. Then she changed it and said, 'after air carrier X passes right to left, turn right on taxiway B, hold short of runway 19L.' this sounded like we could turn directly onto taxiway B from where we were. At this part of the ramp the 2 light poles are behind us, casting our shadow in front of us. There are also no blue taxiway edge lights to define the edges of the txwys. As we got the instructions, the captain began making his right turn and I quickly glanced down at my chart to ensure I knew the taxi instructions. Right now, there was no way to see the ditch. It was not until the nose gear had come around to the right, bringing the taxi light with it, that we could see the white colored concrete of the drainage ditch (it runs directly between taxiway B and taxiway C and is parallel to them - - would have been a good mention in the NOTAMS, or should be depicted on the airport diagram). Anyway, by the time we noticed it, the nose gear was going over the front edge and with the momentum of the aircraft, it continued across and back up the other side. The sides of the ditch were sloped rather than a dropoff. Other than just the rough ride going through it, at no time did we hear any unusual noises, see any abnormal indications, or feel anything out of the ordinary with the aircraft. The lead flight attendant called to ask what had happened and we told her and made a PA to the passenger. No one, flight attendants or passenger, gave any indication that they had seen or heard anything either, other than the rough ride through the ditch. We still had a long taxi remaining and everything seemed normal. We discussed it and agreed that there was no reason not to continue. It was not until we arrived at our destination that the oncoming crew noticed that our right outboard slat had sustained damage. As we looked back on what happened, it appears that the captain mistook taxiway C4 (the taxiway label on the airport diagram chart) for spot 4 on the ramp chart. And since the ground controller's instructions started with 'turn right on taxiway B,' it simply reinforced this belief. However, blue edge lights would have easily prevented this. It is unbelievable that an unlit ditch could be placed right between 2 txwys, and no edge lights are installed around it. Also, this was the last leg of a 4-DAY rotation which had report times of XC20 on aug/xx/98, XB00 on aug/yy/98, and XA40 on aug/zz/98 followed by a 10 hour 4 min rest period (not including travel time to/from the hotel) in the middle of the day, and then 2 legs (slc-las and las-cvg) in the middle of the night. I don't think any one of us could have possibly felt completely rested for that flight. Supplemental information from acn 410494: I then consulted my chart to make sure of the taxi routing and at this time misidented taxiway C4 as our location. We taxied straight ahead for a direct turn onto taxiway B. Without warning we found ourselves heading across a concrete ditch. Factors: 1) no taxiway edge lights in las. Las is notorious as a 'black hole' with very poor taxi conditions and lighting. 2) fatigue -- rotation has XC40 shows, XB00 show, and XA40 show, with 10 hour layover followed by 2 leg all-nighter (captain 2 hours sleep, first officer 1 hour, so 3 hours). First officer commuter from lax, so whole trip on the back side. 3) ramp spots are not on 10-9 chart. The spots are numbered 1-7 and the txwys are C1-C7 but they are not co-located. 4) controller's taxi instructions reinforced our mistake and may have been wrong. Supplemental information from acn 410493: possible factors contributing: 1) lack of adequate lighting on the ramp/taxiway area. 2) change in taxi instructions following runway change. 3) type of rotation -- ie, XC20 report on aug/xx/98, XB40 report on aug/yy/98, XA40 report on aug/zz/98 followed by a 10 hour break in the middle of the day and then 2 legs to complete the rotation in the middle of the night.

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Original NASA ASRS Text

Title: B727 CREW CROSSED A DRAINAGE DITCH AT LAS.

Narrative: AT ABOUT XA00 ON AUG/XA/98, WE PUSHED BACK OUT OF GATE XX AT LAS AND WERE DIRECTED BY RAMP TWR TO TAXI TO SPOT 4. WHILE TAXIING OUT OF THE RAMP, WE WERE EXTRA VIGILANT DUE TO THE FACT THAT OUR NOTAMS HAD HIGHLIGHTED 2 HAZARDS IN THE AREA: 1) 2 LIGHT POLES IN THE CTR OF THE RAMP, AND 2) A DITCH IN THE AREA. PRIOR TO LEAVING THE GATE, I RECALL ASKING THE CAPT IF HE KNEW WHERE THIS DITCH WAS AND HE STATED THAT HE DID NOT. THE NOTAM ONLY SAID SOMETHING TO THIS EFFECT: CAUTION -- THERE IS A DITCH LOCATED DIRECTLY IN FRONT OF THE TERMINAL AND IT IS VERY DIFFICULT TO SEE. IT GAVE NO INDICATION WHERE IN FRONT ON THE TERMINAL IT WAS, AND SEEMED TO IMPLY THAT IT WAS CLOSE TO THE TERMINAL. JUST PRIOR TO PUSHBACK, I COPIED THE NEW ATIS AND TOLD THE OTHERS THAT THE WINDS WERE NOW BEING RPTED AS 130 DEGS AT 6 KTS, BUT THE DUTY RWY WAS STILL RWY 25R. DUE TO OUR WT AND THE HIGH OUTSIDE AIR TEMP, WE WOULD PROBABLY NOT BE ABLE TO USE RWY 25R WITH THAT TAILWIND. AS WE GOT TO SPOT 4, I ASKED THE GND CTLR WHAT THE CURRENT WINDS WERE AND SHE SAID THAT THEY WERE 130 DEGS AT 5 KTS. I ASKED HER TO STANDBY WHILE WE CHKED OUR PERFORMANCE DATA. WHILE THE SO DID THAT, THE CAPT AND I SWITCHED FROM OUR RAMP DIAGRAM (COMPANY CHART) TO THE ARPT DIAGRAM. THE SO THEN INFORMED US THAT WE WOULD NEED RWY 7L OR RWY 7R, PREFERABLY RWY 7L. I PASSED THAT ON TO THE GND CTLR AND SHE GAVE US OUR TAXI INSTRUCTIONS. INITIALLY, SHE SAID TO TURN L ON TXWY C, R ON TXWY C5, R ON TXWY B, AND HOLD SHORT OF RWY 19L. THEN SHE CHANGED IT AND SAID, 'AFTER ACR X PASSES R TO L, TURN R ON TXWY B, HOLD SHORT OF RWY 19L.' THIS SOUNDED LIKE WE COULD TURN DIRECTLY ONTO TXWY B FROM WHERE WE WERE. AT THIS PART OF THE RAMP THE 2 LIGHT POLES ARE BEHIND US, CASTING OUR SHADOW IN FRONT OF US. THERE ARE ALSO NO BLUE TXWY EDGE LIGHTS TO DEFINE THE EDGES OF THE TXWYS. AS WE GOT THE INSTRUCTIONS, THE CAPT BEGAN MAKING HIS R TURN AND I QUICKLY GLANCED DOWN AT MY CHART TO ENSURE I KNEW THE TAXI INSTRUCTIONS. RIGHT NOW, THERE WAS NO WAY TO SEE THE DITCH. IT WAS NOT UNTIL THE NOSE GEAR HAD COME AROUND TO THE R, BRINGING THE TAXI LIGHT WITH IT, THAT WE COULD SEE THE WHITE COLORED CONCRETE OF THE DRAINAGE DITCH (IT RUNS DIRECTLY BTWN TXWY B AND TXWY C AND IS PARALLEL TO THEM - - WOULD HAVE BEEN A GOOD MENTION IN THE NOTAMS, OR SHOULD BE DEPICTED ON THE ARPT DIAGRAM). ANYWAY, BY THE TIME WE NOTICED IT, THE NOSE GEAR WAS GOING OVER THE FRONT EDGE AND WITH THE MOMENTUM OF THE ACFT, IT CONTINUED ACROSS AND BACK UP THE OTHER SIDE. THE SIDES OF THE DITCH WERE SLOPED RATHER THAN A DROPOFF. OTHER THAN JUST THE ROUGH RIDE GOING THROUGH IT, AT NO TIME DID WE HEAR ANY UNUSUAL NOISES, SEE ANY ABNORMAL INDICATIONS, OR FEEL ANYTHING OUT OF THE ORDINARY WITH THE ACFT. THE LEAD FLT ATTENDANT CALLED TO ASK WHAT HAD HAPPENED AND WE TOLD HER AND MADE A PA TO THE PAX. NO ONE, FLT ATTENDANTS OR PAX, GAVE ANY INDICATION THAT THEY HAD SEEN OR HEARD ANYTHING EITHER, OTHER THAN THE ROUGH RIDE THROUGH THE DITCH. WE STILL HAD A LONG TAXI REMAINING AND EVERYTHING SEEMED NORMAL. WE DISCUSSED IT AND AGREED THAT THERE WAS NO REASON NOT TO CONTINUE. IT WAS NOT UNTIL WE ARRIVED AT OUR DEST THAT THE ONCOMING CREW NOTICED THAT OUR R OUTBOARD SLAT HAD SUSTAINED DAMAGE. AS WE LOOKED BACK ON WHAT HAPPENED, IT APPEARS THAT THE CAPT MISTOOK TXWY C4 (THE TXWY LABEL ON THE ARPT DIAGRAM CHART) FOR SPOT 4 ON THE RAMP CHART. AND SINCE THE GND CTLR'S INSTRUCTIONS STARTED WITH 'TURN R ON TXWY B,' IT SIMPLY REINFORCED THIS BELIEF. HOWEVER, BLUE EDGE LIGHTS WOULD HAVE EASILY PREVENTED THIS. IT IS UNBELIEVABLE THAT AN UNLIT DITCH COULD BE PLACED RIGHT BTWN 2 TXWYS, AND NO EDGE LIGHTS ARE INSTALLED AROUND IT. ALSO, THIS WAS THE LAST LEG OF A 4-DAY ROTATION WHICH HAD RPT TIMES OF XC20 ON AUG/XX/98, XB00 ON AUG/YY/98, AND XA40 ON AUG/ZZ/98 FOLLOWED BY A 10 HR 4 MIN REST PERIOD (NOT INCLUDING TRAVEL TIME TO/FROM THE HOTEL) IN THE MIDDLE OF THE DAY, AND THEN 2 LEGS (SLC-LAS AND LAS-CVG) IN THE MIDDLE OF THE NIGHT. I DON'T THINK ANY ONE OF US COULD HAVE POSSIBLY FELT COMPLETELY RESTED FOR THAT FLT. SUPPLEMENTAL INFO FROM ACN 410494: I THEN CONSULTED MY CHART TO MAKE SURE OF THE TAXI ROUTING AND AT THIS TIME MISIDENTED TXWY C4 AS OUR LOCATION. WE TAXIED STRAIGHT AHEAD FOR A DIRECT TURN ONTO TXWY B. WITHOUT WARNING WE FOUND OURSELVES HDG ACROSS A CONCRETE DITCH. FACTORS: 1) NO TXWY EDGE LIGHTS IN LAS. LAS IS NOTORIOUS AS A 'BLACK HOLE' WITH VERY POOR TAXI CONDITIONS AND LIGHTING. 2) FATIGUE -- ROTATION HAS XC40 SHOWS, XB00 SHOW, AND XA40 SHOW, WITH 10 HR LAYOVER FOLLOWED BY 2 LEG ALL-NIGHTER (CAPT 2 HRS SLEEP, FO 1 HR, SO 3 HRS). FO COMMUTER FROM LAX, SO WHOLE TRIP ON THE BACK SIDE. 3) RAMP SPOTS ARE NOT ON 10-9 CHART. THE SPOTS ARE NUMBERED 1-7 AND THE TXWYS ARE C1-C7 BUT THEY ARE NOT CO-LOCATED. 4) CTLR'S TAXI INSTRUCTIONS REINFORCED OUR MISTAKE AND MAY HAVE BEEN WRONG. SUPPLEMENTAL INFO FROM ACN 410493: POSSIBLE FACTORS CONTRIBUTING: 1) LACK OF ADEQUATE LIGHTING ON THE RAMP/TXWY AREA. 2) CHANGE IN TAXI INSTRUCTIONS FOLLOWING RWY CHANGE. 3) TYPE OF ROTATION -- IE, XC20 RPT ON AUG/XX/98, XB40 RPT ON AUG/YY/98, XA40 RPT ON AUG/ZZ/98 FOLLOWED BY A 10 HR BREAK IN THE MIDDLE OF THE DAY AND THEN 2 LEGS TO COMPLETE THE ROTATION IN THE MIDDLE OF THE NIGHT.

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.