PORTLAND, OR, USA
N173DZ
Boeing 767-332ER
About five to 10 minutes after the flight attendants began cabin service, the aircraft entered an area of light to moderate turbulence. The flight crew directed the flight attendants to discontinue cabin service and take their seats, and initiated a descent to an altitude where the air was reported smooth. The flight attendants were in the process of attempting to stow a beverage cart in the aft galley when the aircraft encountered turbulence that momentarily subjected the aircraft to negative G forces. The unseated flight attendants were thrown up off the floor in this encounter, with at least one flight attendant striking her head on the ceiling. The unsecured beverage cart landed on top of this flight attendant's foot, fracturing bones in her foot. Three other flight attendants received minor injuries. The flight crew reported that this encounter occurred in the descent just above flight level (FL) 330, about 90 miles east of the Kimberly, Oregon (IMB) VORTAC. Upon being notified of this situation, the flight crew initiated actions to deal with the situation, and continued on to the flight's destination with the remainder of the flight proceeding uneventfully.
On November 4, 2000, approximately 1115 Pacific standard time, a Boeing 767-332ER, N173DZ, operating as Delta Air Lines flight 1063 on a 14 CFR 121 scheduled domestic passenger/cargo flight from Salt Lake City, Utah, to Portland, Oregon, encountered moderate turbulence during descent at approximately flight level 330 (FL 330) about 90 miles east of the Kimberly, Oregon, VORTAC. In the turbulence encounter, one of the six flight attendants was seriously injured, and three flight attendants received minor injuries. There were no injuries to the other two flight attendants, the airline transport pilot-in-command or first officer, or 176 passengers aboard the aircraft. Following the turbulence encounter, the flight continued to Portland and landed without further incident. The aircraft was not damaged in the occurrence. Visual meteorological conditions were reported at Ontario, Oregon, at 1253 mountain standard time, and the flight was on an instrument flight rules flight plan. The flight's weather package, a copy of which Delta furnished to the NTSB, indicated that light to moderate turbulence was forecast in the area and altitudes where the turbulence encounter actually occurred. A National Weather Service surface analysis chart issued at 1935 Coordinated Universal Time (UTC) also indicated the presence of a generally northwest-southeast oriented cold front across central Oregon. The captain reported that the flight's On-Board Leader (OBL), the lead flight attendant, was briefed before the flight on the possibility of turbulence en route, and that the first officer was the pilot flying on the accident flight. The flight crew reported that after takeoff, they climbed to the flight's cruise altitude of FL 350. They reported that on climbout, the flight attendants called and asked whether it was OK to begin cabin service, and that since they were experiencing "very light chop" at that time, the captain advised them to "use their best judgment regarding whether or not to continue cabin service at that time." The captain reported that at FL 350, about 150 miles east of the Kimberly, Oregon (IMB) VORTAC, the flight began to encounter light to moderate turbulence. He stated that the flight attendants were seated and the seat belt sign was on at that time. The flight crew reported that at this time, ATC was reporting turbulence from FL 230 to FL 390, but at about this time, a Learjet in the area reported that FL 410 was smooth. The crew then requested and received clearance to climb to FL 410. The crew reported that after a couple of minutes of smooth air at FL 410, the flight attendants were advised that it was OK to attempt cabin service. The crew reported that approximately five minutes later, the flight again began to encounter light turbulence. The captain reported that he again seated the flight attendants and made a PA announcement to the passengers that the flight attendants would be taking their seats. The crew then requested and received clearance to descend to FL 310, where it was reported to be smooth. The crew reported that it became smooth when passing approximately FL 370, but that they entered light to moderate turbulence at FL 350. The crew reported that the first officer then extended the speed brakes to increase the rate of descent. The crew reported that the aircraft was flying at its turbulence penetration airspeed of 0.78 Mach at this time. The crew stated that just above FL 330 (approximately FL 333 according to the first officer), the flight encountered two momentary moderate jolts. The flight subsequently leveled off at FL 310 in smooth air. The crew stated that they were then notified that one or more flight attendants had been injured in the aft galley. The crew reported they then took actions to deal with this situation, and that the remainder of the flight was uneventful. The flight attendant who received the serious injury (fractured bones in her foot) reported that she was asked to sit in the mid cabin. She reported that after the flight reached 10,000 feet, while the climbout safety video was playing, "the aircraft began to shake a little." She stated that she told another flight attendant seated with her to stay seated, and that she called to the aft galley and informed other flight attendants that she and her partner at mid-cabin would not be walking to the aft galley until she heard from the aft galley attendants that it was smoother. She stated that the aft galley attendants agreed with this plan. The seriously injured flight attendant reported that she then called the cockpit to see how long the turbulence was expected to last, and "was told that it shouldn't last too long and it probably would not get worse than it was right now." She stated that she informed the cockpit crew that the flight attendants would remain seated. She reported that the flight attendants in the aft galley then called and reported that it had smoothed out enough for cabin service to begin. She reported that the flight attendants then began cabin service. She stated that the aircraft started to hit some bumps about 10 minutes after initiation of cabin service. Shortly thereafter, the flight attendants were instructed to take their seats. She and her partner then returned their beverage cart to the aft galley. She reported that they were in the process of attempting to stow the cart in the aft galley when the aircraft encountered turbulence that sent the unseated flight attendants up off the floor. She reported that she hit the ceiling with her head, then came down with the cart in front of her. She stated that the aircraft was then "hit with a violent side movement" and the cart then landed on top of her foot. A readout of the aircraft's flight data recorder (FDR), accomplished by Delta, disclosed that at a recorder relative time of 55 hours 16 minutes 9 seconds, the aircraft experienced a vertical acceleration of -0.289 G. According to the FDR data, the aircraft was at an altitude of 32,985 feet and airspeed of 279 knots at the time this reading was recorded. The eight vertical accelerations recorded at relative time 55:16:08, the second immediately preceding the -0.289 G reading, were, sequentially, 0.845, 0.978, 1.044, 1.120, 1.127, 1.001, 0.760, and 0.094 G. The seven vertical acceleration readings at relative time 55:16:09, immediately following the -0.289 G reading, were, sequentially, 0.089, 0.737, 1.019, 1.333, 1.573, 1.422, and 1.262 G. The NTSB investigator-in-charge calculated the aircraft's Mach number at the time of the -0.289 G vertical acceleration reading using a manual flight computer and handheld scientific calculator. The computation was based on the following: calibrated airspeed of 279 knots and altitude of 32,985 feet (as per the FDR data); compressibility correction factor of 0.94; and temperature of -51 degrees C (approximate standard atmospheric temperature at 33,000 feet.) Based on this data, the aircraft's Mach number was calculated to be 0.78, the figure reported by the captain.
An inflight encounter with turbulence that occurred before flight attendants could finish stowing a beverage cart and return to their seats.
Source: NTSB Aviation Accident Database
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