Narrative:

Flight XXX on sep/xx/97. Approximately XA30Z between NM and atras FL350, 6:30S 175:30E encountered a dry cumulo nimbus and resulting turbulence. First indication was thin cloud layer visible from strobe lights. Moderate and greater turbulence began about 15 seconds later and lasted about 90 seconds. Radar was on and operating at maximum gain and tilt at 3-4 degrees down. At first indication of cloud scanned radar antenna up and down and found a very weak return close in with antenna 10+ degrees down. Immediate left turn had been made but still encountered the top of the cell. A major area of WX was observed approximately 120 NM ahead of the cell we encountered. Cockpit was dark and no lightning activity was seen. Seat belt sign were turned on at first indication of turbulence but this gave only about 15 seconds warning. Left autoplt engaged and had altitude deviation of about 400 ft. No heavy loads imposed on aircraft. Bunk in flight attendant bunk room upper left side for/aft alignment came apart with flight attendant attached by seat belt. Sfo maintenance had been in bunk room prior to pushback checking circuit breakers. I suspect that the bunk had not been put back together properly. 8 passenger and 4 flight attendants received minor injuries. Contacted company by satcom and coordinated appropriate action and gave details of injuries. Complete passenger and flight attendant details available from dispatch and or cabin. Flight attendants to be complimented for a superb job dealing with this situation. Addendum -- flight attendant bunk room: the upper left for/aft aligned bunk appeared to have been not been fastened at both ends and broke loose during the turbulence as a result. The latches for the locks are under the mattress and the mattress must be removed to access them. The return flight xaa syd-sfo we had xbb, also an air carrier aircraft. I briefed the flight attendants about the latch problem and had the purser check the bunk, he found that it was not latched at one end. I feel this is a real safety problem that needs to be addressed without delay. I spoke with the manager of flight attendant sunday morning and suggested that he make sure that the word gets out to the flight attendants that are flying the airplanes in briefing as a stopgap measure. Radar: I now believe that the airplane xcc may have some shortcomings with the radar. Looking back in the maintenance history I found that the radome had been changed. The inability to detect the dry cumulo nimbus may have been exasperated by a radome with high attenuation in the lower part possible from paint or defect and or the gain tracking of the radar may have been incorrect. No significant difference was noted when switching from system 1-2. Callback conversation with reporter revealed the following information: reporter expressed how dark the night was. No moon, everything was without any illumination. He felt the turbulence start and then build to severe turbulence within 15 seconds. Fortunately the seat belt sign had already been turned on. It didn't feel too bad from the cockpit. Reporter was eating a meal and had no problem keeping all the liquids from moving about on his food tray. The flight attendants in the forward part of the aircraft didn't feel much turbulence. They actually rated the turbulence as light. However, the injuries were in the back of the aircraft. One passenger was leaving the lavatory at the time and he was thrown towards the ceiling, his head being cut as it struck the overhead door jam. Other passenger injuries were from passenger not being tightly buckled into their seat. In the upstairs bunk room at the base of the rudder, it was very rough. One of the bunks was loose and fell off of the wall. Another flight attendant was thrown upwards into a bunk and suffered a blow to the head. There were no broken bones but there were sprains and strains. While all this was going on, there was no spilling of fluids in the cockpit. Supplemental information from acn 379917: in the cockpit the turbulence felt like moderate and drinks stayed in the cups. In the aft of the aircraft 4 flight attendants and approximately 8 passenger were injured. At least 2 of the flight attendants were in the aft crew rest area with seat belts on. One upper bunk came loose from its mounts and fell to the floor. The flight attendant in this bunk was injured but the one below her in the lower bunk was not. This upper bunk had been moved by maintenance prior to flight to access a circuit breaker panel. One of the other flight attendants belted in a lower bunk hit her head on support frame of the upper bunk and was cut on the scalp. A passenger leaving the john hit his head on the ceiling and was also cut on the head. One other passenger received a burn from spilling tea. All other injuries were neck and shoulder strains. Those were the most severe injuries, evaluated by a doctor on board and later taken to a sydney, australia, hospital, x-rayed and released. Every flight attendant, even those not injured said hand-holds in the bunk room by the beds would have helped prevent injury. Back to the front, it was smooth until we entered the cirrus cloud. At that point we encountered light turbulence and the captain turned on the seat belt sign. Within 15-20 seconds we hit 2-3 jolts of moderate turbulence and the aircraft climbed 300-400 ft while the autoplt was engaged. We continued in light-moderate turbulence for another 5-10 mins. It appeared all injuries occurred in the first 2-3 jolts of moderate turbulence. Both the captain and I believe we encountered the icy cirrus top of the dissipating thunderstorm. No lightning was noted but we did have static and st elmo's fire. When the radar tilt was lowered to 6-7 degrees down we did get a green only return. Running the tilt down might have helped. I also know that what turbulence does to a B747 is very much worse in the back of the aircraft.

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Original NASA ASRS Text

Title: A B747-400 ENCOUNTERS SEVERE TURB IN NADI AIRSPACE. 8 PAX AND 4 CABIN ATTENDANTS ARE INJURED.

Narrative: FLT XXX ON SEP/XX/97. APPROX XA30Z BTWN NM AND ATRAS FL350, 6:30S 175:30E ENCOUNTERED A DRY CUMULO NIMBUS AND RESULTING TURB. FIRST INDICATION WAS THIN CLOUD LAYER VISIBLE FROM STROBE LIGHTS. MODERATE AND GREATER TURB BEGAN ABOUT 15 SECONDS LATER AND LASTED ABOUT 90 SECONDS. RADAR WAS ON AND OPERATING AT MAX GAIN AND TILT AT 3-4 DEGS DOWN. AT FIRST INDICATION OF CLOUD SCANNED RADAR ANTENNA UP AND DOWN AND FOUND A VERY WEAK RETURN CLOSE IN WITH ANTENNA 10+ DEGS DOWN. IMMEDIATE L TURN HAD BEEN MADE BUT STILL ENCOUNTERED THE TOP OF THE CELL. A MAJOR AREA OF WX WAS OBSERVED APPROX 120 NM AHEAD OF THE CELL WE ENCOUNTERED. COCKPIT WAS DARK AND NO LIGHTNING ACTIVITY WAS SEEN. SEAT BELT SIGN WERE TURNED ON AT FIRST INDICATION OF TURB BUT THIS GAVE ONLY ABOUT 15 SECONDS WARNING. L AUTOPLT ENGAGED AND HAD ALTDEV OF ABOUT 400 FT. NO HVY LOADS IMPOSED ON ACFT. BUNK IN FLT ATTENDANT BUNK ROOM UPPER L SIDE FOR/AFT ALIGNMENT CAME APART WITH FLT ATTENDANT ATTACHED BY SEAT BELT. SFO MAINT HAD BEEN IN BUNK ROOM PRIOR TO PUSHBACK CHKING CIRCUIT BREAKERS. I SUSPECT THAT THE BUNK HAD NOT BEEN PUT BACK TOGETHER PROPERLY. 8 PAX AND 4 FLT ATTENDANTS RECEIVED MINOR INJURIES. CONTACTED COMPANY BY SATCOM AND COORDINATED APPROPRIATE ACTION AND GAVE DETAILS OF INJURIES. COMPLETE PAX AND FLT ATTENDANT DETAILS AVAILABLE FROM DISPATCH AND OR CABIN. FLT ATTENDANTS TO BE COMPLIMENTED FOR A SUPERB JOB DEALING WITH THIS SIT. ADDENDUM -- FLT ATTENDANT BUNK ROOM: THE UPPER L FOR/AFT ALIGNED BUNK APPEARED TO HAVE BEEN NOT BEEN FASTENED AT BOTH ENDS AND BROKE LOOSE DURING THE TURB AS A RESULT. THE LATCHES FOR THE LOCKS ARE UNDER THE MATTRESS AND THE MATTRESS MUST BE REMOVED TO ACCESS THEM. THE RETURN FLT XAA SYD-SFO WE HAD XBB, ALSO AN ACR ACFT. I BRIEFED THE FLT ATTENDANTS ABOUT THE LATCH PROB AND HAD THE PURSER CHK THE BUNK, HE FOUND THAT IT WAS NOT LATCHED AT ONE END. I FEEL THIS IS A REAL SAFETY PROB THAT NEEDS TO BE ADDRESSED WITHOUT DELAY. I SPOKE WITH THE MGR OF FLT ATTENDANT SUNDAY MORNING AND SUGGESTED THAT HE MAKE SURE THAT THE WORD GETS OUT TO THE FLT ATTENDANTS THAT ARE FLYING THE AIRPLANES IN BRIEFING AS A STOPGAP MEASURE. RADAR: I NOW BELIEVE THAT THE AIRPLANE XCC MAY HAVE SOME SHORTCOMINGS WITH THE RADAR. LOOKING BACK IN THE MAINT HISTORY I FOUND THAT THE RADOME HAD BEEN CHANGED. THE INABILITY TO DETECT THE DRY CUMULO NIMBUS MAY HAVE BEEN EXASPERATED BY A RADOME WITH HIGH ATTENUATION IN THE LOWER PART POSSIBLE FROM PAINT OR DEFECT AND OR THE GAIN TRACKING OF THE RADAR MAY HAVE BEEN INCORRECT. NO SIGNIFICANT DIFFERENCE WAS NOTED WHEN SWITCHING FROM SYS 1-2. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR EXPRESSED HOW DARK THE NIGHT WAS. NO MOON, EVERYTHING WAS WITHOUT ANY ILLUMINATION. HE FELT THE TURB START AND THEN BUILD TO SEVERE TURB WITHIN 15 SECONDS. FORTUNATELY THE SEAT BELT SIGN HAD ALREADY BEEN TURNED ON. IT DIDN'T FEEL TOO BAD FROM THE COCKPIT. RPTR WAS EATING A MEAL AND HAD NO PROB KEEPING ALL THE LIQUIDS FROM MOVING ABOUT ON HIS FOOD TRAY. THE FLT ATTENDANTS IN THE FORWARD PART OF THE ACFT DIDN'T FEEL MUCH TURB. THEY ACTUALLY RATED THE TURB AS LIGHT. HOWEVER, THE INJURIES WERE IN THE BACK OF THE ACFT. ONE PAX WAS LEAVING THE LAVATORY AT THE TIME AND HE WAS THROWN TOWARDS THE CEILING, HIS HEAD BEING CUT AS IT STRUCK THE OVERHEAD DOOR JAM. OTHER PAX INJURIES WERE FROM PAX NOT BEING TIGHTLY BUCKLED INTO THEIR SEAT. IN THE UPSTAIRS BUNK ROOM AT THE BASE OF THE RUDDER, IT WAS VERY ROUGH. ONE OF THE BUNKS WAS LOOSE AND FELL OFF OF THE WALL. ANOTHER FLT ATTENDANT WAS THROWN UPWARDS INTO A BUNK AND SUFFERED A BLOW TO THE HEAD. THERE WERE NO BROKEN BONES BUT THERE WERE SPRAINS AND STRAINS. WHILE ALL THIS WAS GOING ON, THERE WAS NO SPILLING OF FLUIDS IN THE COCKPIT. SUPPLEMENTAL INFO FROM ACN 379917: IN THE COCKPIT THE TURB FELT LIKE MODERATE AND DRINKS STAYED IN THE CUPS. IN THE AFT OF THE ACFT 4 FLT ATTENDANTS AND APPROX 8 PAX WERE INJURED. AT LEAST 2 OF THE FLT ATTENDANTS WERE IN THE AFT CREW REST AREA WITH SEAT BELTS ON. ONE UPPER BUNK CAME LOOSE FROM ITS MOUNTS AND FELL TO THE FLOOR. THE FLT ATTENDANT IN THIS BUNK WAS INJURED BUT THE ONE BELOW HER IN THE LOWER BUNK WAS NOT. THIS UPPER BUNK HAD BEEN MOVED BY MAINT PRIOR TO FLT TO ACCESS A CIRCUIT BREAKER PANEL. ONE OF THE OTHER FLT ATTENDANTS BELTED IN A LOWER BUNK HIT HER HEAD ON SUPPORT FRAME OF THE UPPER BUNK AND WAS CUT ON THE SCALP. A PAX LEAVING THE JOHN HIT HIS HEAD ON THE CEILING AND WAS ALSO CUT ON THE HEAD. ONE OTHER PAX RECEIVED A BURN FROM SPILLING TEA. ALL OTHER INJURIES WERE NECK AND SHOULDER STRAINS. THOSE WERE THE MOST SEVERE INJURIES, EVALUATED BY A DOCTOR ON BOARD AND LATER TAKEN TO A SYDNEY, AUSTRALIA, HOSPITAL, X-RAYED AND RELEASED. EVERY FLT ATTENDANT, EVEN THOSE NOT INJURED SAID HAND-HOLDS IN THE BUNK ROOM BY THE BEDS WOULD HAVE HELPED PREVENT INJURY. BACK TO THE FRONT, IT WAS SMOOTH UNTIL WE ENTERED THE CIRRUS CLOUD. AT THAT POINT WE ENCOUNTERED LIGHT TURB AND THE CAPT TURNED ON THE SEAT BELT SIGN. WITHIN 15-20 SECONDS WE HIT 2-3 JOLTS OF MODERATE TURB AND THE ACFT CLBED 300-400 FT WHILE THE AUTOPLT WAS ENGAGED. WE CONTINUED IN LIGHT-MODERATE TURB FOR ANOTHER 5-10 MINS. IT APPEARED ALL INJURIES OCCURRED IN THE FIRST 2-3 JOLTS OF MODERATE TURB. BOTH THE CAPT AND I BELIEVE WE ENCOUNTERED THE ICY CIRRUS TOP OF THE DISSIPATING TSTM. NO LIGHTNING WAS NOTED BUT WE DID HAVE STATIC AND ST ELMO'S FIRE. WHEN THE RADAR TILT WAS LOWERED TO 6-7 DEGS DOWN WE DID GET A GREEN ONLY RETURN. RUNNING THE TILT DOWN MIGHT HAVE HELPED. I ALSO KNOW THAT WHAT TURB DOES TO A B747 IS VERY MUCH WORSE IN THE BACK OF THE ACFT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.