BOEING 767 332Delta Air Lines
San Juan, PR, USA · 2009-05-20·N129DL
What happened
NTSB summary, verbatimOn May 20, 2009, at 1230 eastern daylight time, Delta Airlines flight 419, a Boeing 767, N129DL, encountered turbulence while enroute from Atlanta, Georgia, to San Juan, Puerto Rico. The captain stated that preflight information and enroute reports indicated only light chop for the flight and he communicated this to the flight attendants. About 10 minutes before the turbulence encounter, the captain turned on the seat belt sign and made an announcement for the passengers to remain in their seats with the seat belt fastened because they would be deviating around weather ahead. After deviating around the weather and with no weather returns on the radar, the flight encountered turbulence that lasted for about 20 seconds. At the time of the turbulence encounter, the airplane was in cruise at Flight Level 350. One of the flight attendants in the back of the airplane was thrown from her jump seat to the floor and injured. Two doctors and a nurse assisted the injured flight attendant. The flight crew declared an emergency and was given direct routing to San Juan. The injured flight attendant was transported to the hospital, where she was subsequently diagnosed with a fractured femur.
Photographs
1the aircraft, and what the investigators foundProbable cause
the Board's determinationInadvertent encounter with convective turbulence while in cruise.
Occurrence sequence
1 stepsNTSB coding · CICTT taxonomy- 1 · Enroute-cruiseTurbulence encounterdefining event
Findings
1 causal · 0 contributing- CAUSEEnvironmental issues › Conditions/weather/phenomena › Turbulence › Convective turbulence — Effect on personnel
Sequence of events
5 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)- about 2 h 20 min after takeoffcruisep.3Cruising at 37,000 ft at approximately 260 knots indicated, the airplane descended to 35,000 ft
- about 3 minutes latercruisep.3Rapidly changing lateral and vertical accelerations for approximately 20 seconds; the airplane rolled 25 degrees right and pitched down 2 degrees before returning to its previous attitude; autopilot engaged throughout
- onset of eventcruisep.3Elevators jostled then returned; outboard ailerons fixed while inboard ailerons deflected toward a right roll; rudder deflected right; no rudder pedal or column input; control wheel deflected 10 degrees right concurrent with the inboard aileron deflection; no slat or flap deployment
- eventcruisep.3Maximum lateral accelerations approximately +0.25 g and -0.10 g; maximum vertical accelerations approximately +1.6 g and +0.5 g; temperature steady while wind speed and direction fluctuated
- about 55 minutes after the eventlandingp.3Flight 419 landed
NTSB analysis
from the final reportOn May 20, 2009, at 1230 eastern daylight time, Delta Airlines flight 419, a Boeing 767, N129DL, encountered turbulence while enroute from Atlanta, Georgia, to San Juan, Puerto Rico. The captain stated that preflight information and enroute reports indicated only light chop for the flight and he communicated this to the flight attendants. About 10 minutes before the turbulence encounter, the captain turned on the seat belt sign and made an announcement for the passengers to remain in their seats with the seat belt fastened because they would be deviating around weather ahead. After deviating around the weather and with no weather returns on the radar, the flight encountered turbulence that lasted for about 20 seconds. At the time of the turbulence encounter, the airplane was in cruise at Flight Level 350. One of the flight attendants in the back of the airplane was thrown from her jump seat to the floor and injured. Two doctors and a nurse assisted the injured flight attendant. The flight crew declared an emergency and was given direct routing to San Juan. The injured flight attendant was transported to the hospital, where she was subsequently diagnosed with a fractured femur.