N76156
BOEING 767-224
The Captain stated that the ride had been smooth at their cruise altitude of 36,000 feet and he was able to see lights on the ground below with good forward visibility as well. The autopilot was engaged, both weather radar devices were on and functioning normally, and the seat belt sign was illuminated. Seconds after he initiated a climb to 38,000 feet, the aircraft encountered an initial severe bump followed by a few seconds of moderate turbulence and a final severe bump within the span of about ten seconds. The aircraft continued to climb and level off at 38,000 feet. The Captain was notified that there were some passenger and flight attendant injuries and made the decision to declare a medical emergency diversion to Miami International Airport in Florida where the aircraft landed one hour and forty minutes later. The FDR data indicated that, upon a climb from 36,000 feet to 38,000 feet, the vertical acceleration changed from 1.0 g’s to 2.0 g’s in one second, continued to oscillate from 2.0 g’s to 0.9’s for seven seconds before returning to 1.0 g’s and then immediately accelerating to -1.0 g’s in 0.5 seconds. No pilot reports near the location and close to the time of the turbulence encounter were found on record, and the weather document issued for the incident flight showed no predicted turbulence activity at the time of the turbulence event in the turbulence region. In addition, a meteorological study using satellite weather imagery at the time of the incident indicated the presence of isolated, rapidly developing cumulus congestus to cumulonimbus clouds under the airplane’s flight path.
HISTORY OF FLIGHT On August 3, 2009, about 0355 eastern daylight time, N76156, a Boeing 767-224, registered to and operated by Continental Airlines Inc., as flight 128, a Title 14 CFR Part 121 international passenger flight from Rio de Janeiro, Brazil (GIG) to Houston Intercontinental Airport (IAH), Houston, Texas, encountered severe turbulence that resulted in multiple injuries, while at an altitude of 36,000 feet. Visual meteorological conditions prevailed in the area at the time, and an instrument flight rules flight plan was filed. Of the 179 passengers and crew on board the flight, several injuries were reported, and the captain diverted the flight and landed in Miami, Florida. According to the Captain, the flight was en route, about 67 nautical miles north of Bavaro, Dominican Republic, and had been in contact with FAA Miami Air Route Traffic Control Center. The captain further stated that the airplane had been cleared to climb from 36,000 feet to 38,000 feet, and upon reaching 36,500 feet, it encountered severe turbulence which lasted about 5 seconds. He said the plane continued to climb to the assigned altitude of 38,000 feet, and the autopilot remained engaged for the whole duration of the occurrence and had not disengaged. At the time, the flight was in night visual meteorological conditions, and the captain said that he could see lights on the ground and there was good forward visibility. Both weather radars had been operating, and were functioning normally, and the seat belt sign was illuminated before, during, and after the occurrence. The relief first officer, who was the pilot flying at the time, stated that he has requested the climb, and after entering the desired altitude in the autopilot system the airplane initiated the climb and then severe turbulence was encountered, which that lasted about five seconds. He further stated that there he looked at the weather radar display and that there were no indications of precipitation in the area. The lead flight attendant, who was in the rear of the airplane, stated that although the seat belt sign had been illuminated for quite awhile, the flight was smooth and they were not experiencing any turbulence. A few minutes after 0350, the lead flight attendant said that he felt 2 to 3 “very large jolts which lasted approximately three seconds.” He further stated that after the turbulence ceased, a passenger who had been returning to her seat from the rear of the aircraft, was found unconscious and bleeding on the deck of the airplane. Another passenger, who was an emergency medical technician, attended to the unconscious passenger, while the lead flight attendant consulted with the captain. The captain subsequently declared a medical emergency and diverted to Miami, Florida where the aircraft landed about one hour and 40 minutes later. INJURIES Several injuries were initially reported and multiple people were transported to the hospital upon arrival in MIA. Following medical assessment, none of the injuries were determined to be serious. DAMAGE TO AIRPLANE Postincident examination of the airplane did not reveal any evidence of substantial damage. FLIGHT RECORDERS The airplane’s flight data recorder (FDR) was sent to the NTSB’s Recorder Laboratory, Washington DC, for readout, and it was found to contain 53 hours of data. The data indicated that as the aircraft began a climb from 36,000 feet, the vertical acceleration changed from 1.0 g to 2.0 g’s in one second, continued to oscillate from 2.0 g’s to 0.9’s for seven seconds before returning to 1.0 g and then immediately accelerating to -1.0 g in 0.5 seconds. The data also showed that the airplane’s autopilot had been engaged as the flight crew had described. METEOROLOGICAL INFORMATION An NTSB meteorological specialist conducted a weather study and noted that a tropical easterly wave with a general northwest to southeast orientation was located near where the incident occurred. In addition, examination of satellite weather imagery in the area of the incident flight around the time of the event indicated the presence of isolated, rapidly developing cumulus congestus to cumulonimbus clouds under the airplane’s flight path. No pilot reports near the location and close to the time of the turbulence encounter were found on record. According to the operator, the weather document issued for the incident flight showing weather reports and forecasts along and nearby the flight plan showed no predicted turbulence activity at the time of the turbulence event in the turbulence region. See the NTSB Meteorological Factual Report.
The flight crew's inadvertent flight through the top of a convective updraft that resulted in an encounter with convective induced turbulence. Contributing to the severity of the incident was the unrestrained status of several passengers, contrary to the lighted seat belt sign.
Source: NTSB Aviation Accident Database
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