DALLAS, TX, USA
N910AW
Boeing 757-2G7
While cruising at FL310, the captain observed on radar that the airplane was approaching a line of thunderstorm cells, which had been forecast. The captain advised the first flight attendant to expect turbulence. He turned on the fasten seat belt sign, and he directed that cabin service be suspended and the service carts stowed. The first flight attendant notified the other flight attendants of the captain's instructions. She stated that she directed them to "stop service and take their seats immediately." The flight attendants secured the cabin, which took a few minutes. However, they had not taken their seats when the airplane encountered several jolts of moderate turbulence. The airplane's flight data recorder indicated that within a 1/2-second period the vertical acceleration changed from -0.05G to +2.37Gs. The first flight attendant (front cabin) was knocked off her feet. The three flight attendants in the aft galley were thrown upward but did not strike the ceiling before coming back down and falling to the floor. One was seriously injured. The operator's "InFlight Operations Manual" required the flight crew to use standard terminology during briefings to the flight attendants. The descriptive terms include usage of the words "light, moderate, or severe" when describing expected turbulence. Neither the captain nor any of the flight attendants reported having used/heard these terms regarding the anticipated turbulence intensity.
HISTORY OF FLIGHT On April 2, 2000, about 2206 hours central daylight time (0306 UTC), a Boeing 757-2G7, N910AW, operated by America West Airlines, Inc., as Cactus flight number 563, encountered moderate turbulence while cruising at flight level 310 about 38 nautical miles (nm) south of Dallas, Texas. The airplane was undamaged; however, three flight attendants, who were located in the aft galley, sustained injuries (one serious and two minor), and one flight attendant was not injured. Neither of the 2 pilots nor the 193 passengers (including 3 infants) was injured. The scheduled, domestic, passenger flight was performed under 14 CFR Part 121. Instrument meteorological conditions prevailed, and an instrument flight plan was filed. The flight originated at 2037 eastern daylight time from Orlando, Florida, and it landed without further mishap at 2231 Pacific daylight time in Las Vegas, Nevada. In a written statement received from the captain, he indicated that 5 or 6 minutes prior to experiencing "two strong jolts of turbulence," he had anticipated encountering the turbulence because of the presence of a line of thunderstorms. He indicated that the fasten seatbelt signs were turned on. Additionally, the captain reported that he had contacted the First Flight Attendant and advised her "of the line of storms with the possibility of further turbulence." The captain reported that he "directed that cabin service be suspended, and the [service] carts stowed." In summary, the Director of Operations Safety at America West Airlines reported that flight attendants estimated 3 to 7 minutes after they received the captain's message the turbulence was encountered. The First Flight Attendant (front cabin) was knocked off her feet. The three flight attendants in the aft galley were thrown upward but did not strike the ceiling before coming back down and falling to the floor. Regarding the sequence of events leading to the flight attendants' notifications of turbulence, in a written statement received from the First Flight Attendant (First FA), she indicated that the captain had "called us again to secure our galleys mentioning that we were going to go through some more turbulence." The First FA further reported that she instructed them [the other FAs] to stop service and take their seats immediately." The Second FA made a written statement in which he recalled that the First FA had advised the captain said we needed to take our seats in about 5 minutes because we were going to experience some more bumps. The Second FA indicated that he, and another FA, passed out the two drinks in their hands and headed for the back (of the airplane). They then immediately secured the carts and started to secure the galley. It seemed as if right after the last compartment was secured it (the turbulence) hit. The Third FA reported that the First FA came to Cabin C while they were doing a beverage service. The First FA told her that the captain said they needed to stow the carts and take their jump seats, as it was going to get bumpy. The Third FA additionally reported "we took the carts back in the galley and stowed them along with the cups, and other miscellaneous service items. Right then, we hit severe turbulence." The Fourth FA reported that she heard the First FA's announcement that the captain again "advised of bad weather," and he requested that the FA's stow all service carts and sit down. The Fourth FA's immediate compliance with the instructions was delayed due to her interaction with passengers. METEOROLOGICAL INFORMATION A convective Sigmet (significant meteorological information) was issued at 0155 UTC and was valid until 0355 UTC. Severe thunderstorms with tops to 45,000 feet, 1-inch diameter hail, and 50-knot wind gusts were forecast in Texas. Moderate turbulence was also forecast. Regarding the en route weather conditions, the captain indicated that over eastern Texas he observed a line of cells on the radar. It was a dark night, and the airplane was flying in-and-out of clouds. There was no visible lightning in the immediate area, and no precipitation was observed. The America West Director, Operations Safety, additionally reported that according to the captain, his weather radar indicated the closest large cell was about 20 miles away when they encountered the turbulence that resulted in the flight attendant injuries. Also, the captain reported that he had not received "ride" reports that indicated the possibility of moderate or greater turbulence in the area. A review of air traffic control communications between the flight crew and the Dallas High Altitude radar controller revealed that at 0308:15 UTC a crewmember stated that he "had to turn to miss this cell we're gettin uh we had uh moderate turbulence there." At 0309:30 UTC, a crew member stated "we're gettin pretty uh pretty uh we're gettin moderate uh possibly a little stronger than that." FLIGHT DATA RECORDER AND RADAR INFORMATION Extracted information from the airplane's flight data recorder (FDR) revealed peak vertical accelerations from -0.05G to +2.37G occurred during an approximate 1/2-second time interval from 0306:23 UTC to 0306:24 UTC. (See the FDR printout for additional details.) Federal Aviation Administration recorded radar data indicates that between 0306:27 UTC and 0306:38 UTC, the airplane's transponder indicated a climb from 31,000 feet to 31,100 feet. Between 0306:38 UTC and 0306:58 UTC, the airplane's transponder showed a 300-foot descent. (See the National Track Analysis Plot for additional details.) ADDITIONAL INFORMATION Prior to departure, the captain conducted a crew briefing, which included a warning regarding en route turbulence during the flight. Light intensity turbulence was encountered during the flight prior to the accident event. In the America West Airlines "InFlight Operations Manual" the following procedures are written for crewmembers regarding usage of standard terminology during briefings: "The Captain is to include any information on anticipated or forecast turbulence in the briefing with the 1st Flight Attendant, using the standard terminology of Light Turbulence, Moderate Turbulence, or Severe Turbulence." Regarding in flight procedures, the Manual states the following: "While in flight, the flight deck will communicate with the 1st Flight Attendant if turbulence is expected or encountered. Standard turbulence terminology will be used. The 1st FA will immediately communicate this information to the other flight attendants and prepare the cabin according to the Turbulence Level Chart."
The en route cruise encounter with forecast moderate turbulence.
Source: NTSB Aviation Accident Database
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