N831L

HISTORY OF FLIGHT

On August 8, 1998, about 0012 hours Pacific daylight time, a Boeing 727-2Q8, N831L, operated by Delta Air Lines, Inc., as Flight 190, sustained minor damage when the crew taxied through a drainage ditch en route to runway 7L at the McCarran International Airport (LAS), Las Vegas, Nevada. The 3 flight crewmembers, 3 flight attendants, and 149 passengers were not injured. The flight reported they were unaware of any damage, continued to taxi, and departed. The flight was conducted under 14 CFR Part 121 as a nonstop regularly scheduled domestic passenger flight destined for Covington/Cincinnati/Northern Kentucky International Airport (CVG), near Cincinnati, Ohio. An IFR flight plan was filed.

According to statements from the flight crew, the flight to CVG was normal and landed without incident at the destination. The oncoming flight crew at CVG discovered the damage to the airplane during a preflight walk around. The airplane received scrapes to the No. 1 slat, No. 8 slat, right wing outboard flap track canoe, and, the left and right wing tips. Additional damage included a 5- by 1-inch tear in the right wing skin, scrapes to the trailing edge flaps, and the nosewheel taxi light. Foreign object damage was also noted to the No. 3 engine C1 and C2 fans and the C1 stator and fan exit cases.

On August 12 and 13, 1998, Safety Board investigators and Federal Aviation Administration (FAA) Airworthiness Inspectors from the Las Vegas Flight Standards District Office (FSDO) inspected the ramp area at LAS and the drainage ditch where the incident occurred. Measurements of the 800-foot-long ditch revealed it to be approximately 97 feet wide at the middle of the ditch and 4 feet deep at the deepest point near the middle. Tire marks consistent with the Boeing 727 airplane were found, which entered the ditch at approximately a 45-degree angle to the longitudinal axis of the ditch and exited out the other side. The slope of the ditch sides at the point where the tracks entered was measured at 15 degrees. Impressions and scrape marks dimensionally consistent with the size and shape of the airplane's wing tips were noted on the edges of the ditch and were measured at 102 feet apart. The distance from the left scrape mark to the left tire tracks was 44 feet, and the measurement from the right scrape mark to the right tire tracks was 43 feet. A diagram of the Boeing 727-200 series airplane was located and indicated that the principal dimensions for wingtip to wingtip measurements was 108 feet.

The Safety Board Operations Group interviewed the flight deck crewmembers, the three flight attendants and the chief pilot of Delta in Cincinnati on August 24 and 25th, 1998.

The captain of the flight stated that he was on the last day of a 4-day sequence in Salt Lake City, Utah. He arrived for duty at 2200. He said that the initial outbound airplane had an engine problem and that they substituted airplanes due to a mechanical problem. He stated that he and the first officer checked the paperwork, including a Notice to Airmen (NOTAM) which stated, "Caution new terminal has a ditch located directly from center of terminal that is not easily visible." The captain said the crew discussed the NOTAM and he stated he thought the ditch was two circle shaped areas off the end of Concourse D. None of the flight crew recalled seeing any additional information regarding the ditch other than the NOTAM. The captain said he gave a crew briefing in Salt Lake City, which included instructions to be aware of the poorly marked taxiways in LAS.

The captain stated that they performed a preflight check of the aircraft and pushed back from the gate in Salt Lake City at 2257. The flight from SLC was uneventful and they arrived at LAS at 2314. The captain said they were about 1 hour late out of Salt Lake City, and that they arrived in Las Vegas late. He stated that they were on the ground in Las Vegas "about 45 minutes," and pushed back from the gate about midnight. The captain and the first officer reviewed a complete new set of flight departure paperwork in LAS, which included the NOTAM about the ditch.

The flight was pushed back from the gate at Concourse D. The crew started engine numbers 1 and 2 because the aircraft weighed about 186,000 pounds and the temperature was 97 degrees Fahrenheit. This weight was near the maximum airplane gross weight of 190,000 pounds. The captain said that they accomplished the after-start checklist, then they got taxi clearance to spot 4 from ramp control. Spot 4 was located north of taxiway Charlie (C) between taxiway Charlie 4 (C-4) and taxiway Charlie 3 (C-3). Spot 4 was not depicted on the pilot's airport diagram chart (Jeppesen chart 10-9) or on the McCarran International Airport's airport diagram chart, but was shown on the Delta Airlines Jeppesen chart 10-0B. The captain said he acknowledged to the first officer that he heard the taxi clearance and taxied to spot 4, where he stopped the airplane and the first officer requested taxi clearance from LAS ground control.

The captain said that they originally planned to depart via runway 25R but once they determined that the winds were unfavorable, they asked for a runway change to runway 7L because it was longer and had a greater margin of safety for takeoff. He said that they extended the flaps to the takeoff setting after the first two engines were started and that the after-start checklist was accomplished during taxi and prior to reaching spot 4.

The captain stated that during taxi they had the taxi lights on. During the interview, he was asked if the taxi lights were positioned properly to illuminate the area in front of the airplane, and the captain said that the taxi light was pointing up "slightly." He stated that he didn't think it was important enough to write up for maintenance. The captain said he did not recall seeing any markings or lights on taxiway C. Taxiway C had a painted double yellow line parallel and adjacent to the ditch and a yellow centerline. Taxiway C did not have any centerline lighting or blue taxiway edge lights.

According to the captain, while they were sitting at spot 4, the first officer requested runway 7L. He said that the ground control instructions were to "turn right on Charlie (taxiway C), left on Charlie 5 (taxiway C-5), right on Bravo (taxiway Bravo), and hold short of 19L (runway 19L)." He said that they switched to the airport diagram, (Jeppesen page 10-9), and started to taxi forward to gain momentum for the turn. As he was getting ready to turn the airplane, the ground controller called and stated, "let me make things easier on you . . . after the America West crosses from right to left, turn right on taxiway Bravo (B) and hold short of runway 19L." The captain stopped taxiing the airplane and waited for the America West airplane that was taxiing westbound on taxiway B.

As the captain looked down at the taxiway diagram, he was thinking of spot 4 and confused it with taxiway C4, and proceeded as instructed by ground control to make the right turn on taxiway Bravo. He was asked if he discussed this clearance with anyone else, and he replied, "No." The captain taxied the airplane forward across taxiway C, through the ditch, and made a right turn onto taxiway B. (The distance from spot 4 to the edge of the ditch was subsequently measured at 86 feet.)

The captain said that as he started to taxi ahead and went into the ditch, it felt like a slight depression in the taxiway. He said he felt the bump and started down the ditch, which allowed the taxi light to illuminate the far side of the ditch. He said all of a sudden, he saw a white surface that he thought was concrete. He thought that it was safer to continue across the depression rather than stomping on the brakes at this point. He indicated that he had been on taxiways rougher than what he had just experienced. He said that he did not know it was a ditch when he entered it and thought it was a drainage depression.

After turning onto taxiway Bravo, the captain said, "What was that? We were at C4." He then stated we were at spot 4 not taxiway "C4." He said we must have crossed right here and pointed to an area between C4 and C3 on the airport taxiway diagram. He indicated that there was a group discussion among the pilots and the consensus was that nobody heard anything, felt anything, or saw any unusual lights.

After the airplane turned onto taxiway Bravo, the A-line flight attendant, who was seated on the forward jumpseat, received an interphone call from a flight attendant in the aft section who asked, "what was that?" The A-line flight attendant then tried to call the cockpit, but did not receive a response. The aft flight attendant called the cockpit and informed the pilots that the passengers were concerned and asked the pilots what had happened. She was told by the flight engineer that they had gone through "a dip in the taxiway" and that they would make an announcement. The second officer made the announcement and said that they had just gone over a dip in the taxiway and that there was nothing to be concerned about.

The captain stated that the number 3 engine was started just before takeoff and the engine start was normal. He reported that the approach and landing in Cincinnati was normal and that all shutdown checklists were performed.

The first officer said he called the ramp tower and was cleared to taxi to spot 4. He stated they held at spot 4 and then called ground control and told them that they were at spot 4. He said that after discussing the winds with the other crewmembers they decided to ask for runway 7L. Ground control said, "Turn right on Charlie, left on Charlie 5, right on Bravo, and hold short of 19L." Just as the captain started to taxi, the ground controller said, "Tell you what. Let me make it easy on you. There is an America West from right to left on Bra...