Narrative:

Cruising FL390, .78 mach, on direct course between jan and aex, approximately 80 NM northeast of aex. We were in IMC in a haze layer. Air was smooth and the flight had been smooth the entire flight. There were no echoes on radar other than an occasional light (green) return during the flight. We had no indications visually or on radar of any major thunderstorms or buildups along our route of flight. The only deviations for WX were for some small developments earlier, with deviations never exceeding 10-20 degrees and were not long in duration. During the flight and prior to the turbulence encounter, we had the radar on in WX/T mode. I had exercised the tilt and varied the range between 40-160 mi. No major returns were displayed and no line of developed or increasing thunderstorms were indicated. There were no PIREPS or ATC reports of turbulence in the area. We were flying in a haze layer, and smooth air. As the layer thinned, we noticed a small buildup directly in front of us, which did not appear large or well developed. Its tops appeared to be at our altitude, but had not generated a radar return. There was no way to maneuver around the buildup. We entered the cloud and encountered severe turbulence with strong updrafts. The aircraft gained about 500 ft and rolled approximately 30 degrees right. The first officer, who was the PF, did an excellent job of maintaining positive control of the aircraft without radical control or throttle input. The duration of the encounter was less than 5 seconds. We returned to FL390. The air on the other side was clear with fairly good visibility and smooth. It continued smooth for the duration of the flight. We reported severe turbulence to ATC. I checked with the flight attendants to see if everyone was ok. The lead flight attendant indicated there were some people standing in the aisle when we encountered the turbulence and there were some injuries and that they were tending to them. I requested a call back with more information and the severity of the injuries when able. I called back in a few mins to determine extent of injuries. She indicated some pain, bruises, cuts (4-5 passenger). She indicated 1 passenger was in the lavatory at the time of the turbulence. I asked her opinion if extent of injuries were serious enough to warrant a divert. She said she didn't think so, and indicated the situation was stabilized. (We were about 25 mins out of ZZZ.) I conferred with the first officer and we agreed diversion was unnecessary as to our close proximity to ZZZ. We declared an emergency with injuries on board. We were cleared direct ZZZ. I called dispatch on the air phone and advised them of situation, and requested paramedics meet the aircraft at gate, and a customer service supervisor. I checked with the flight attendants again as to status of passenger and crew. They indicated passenger have ice packs. Nose injury to 1 passenger, possible cuts, bruises, etc. I contacted operations and verified paramedics to meet the aircraft. Landed without further incident. Paramedics met aircraft and attended to passenger. We talked to maintenance at the gate for logbook write-up and again later by phone. Overall, the turbulence encounter was unavoidable, and recovery and control of the event was excellent. Our main objective was control of the aircraft, assess the situation, and coordinate the response. The flight attendants did an excellent job caring for the passenger and stabilizing the situation. The communication with me was excellent. The coordination with ATC and dispatch also went very well and all services met us promptly.

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Original NASA ASRS Text

Title: B737 FLC ENCOUNTERS SEVERE TURB.

Narrative: CRUISING FL390, .78 MACH, ON DIRECT COURSE BTWN JAN AND AEX, APPROX 80 NM NE OF AEX. WE WERE IN IMC IN A HAZE LAYER. AIR WAS SMOOTH AND THE FLT HAD BEEN SMOOTH THE ENTIRE FLT. THERE WERE NO ECHOES ON RADAR OTHER THAN AN OCCASIONAL LIGHT (GREEN) RETURN DURING THE FLT. WE HAD NO INDICATIONS VISUALLY OR ON RADAR OF ANY MAJOR TSTMS OR BUILDUPS ALONG OUR RTE OF FLT. THE ONLY DEVS FOR WX WERE FOR SOME SMALL DEVELOPMENTS EARLIER, WITH DEVS NEVER EXCEEDING 10-20 DEGS AND WERE NOT LONG IN DURATION. DURING THE FLT AND PRIOR TO THE TURB ENCOUNTER, WE HAD THE RADAR ON IN WX/T MODE. I HAD EXERCISED THE TILT AND VARIED THE RANGE BTWN 40-160 MI. NO MAJOR RETURNS WERE DISPLAYED AND NO LINE OF DEVELOPED OR INCREASING TSTMS WERE INDICATED. THERE WERE NO PIREPS OR ATC RPTS OF TURB IN THE AREA. WE WERE FLYING IN A HAZE LAYER, AND SMOOTH AIR. AS THE LAYER THINNED, WE NOTICED A SMALL BUILDUP DIRECTLY IN FRONT OF US, WHICH DID NOT APPEAR LARGE OR WELL DEVELOPED. ITS TOPS APPEARED TO BE AT OUR ALT, BUT HAD NOT GENERATED A RADAR RETURN. THERE WAS NO WAY TO MANEUVER AROUND THE BUILDUP. WE ENTERED THE CLOUD AND ENCOUNTERED SEVERE TURB WITH STRONG UPDRAFTS. THE ACFT GAINED ABOUT 500 FT AND ROLLED APPROX 30 DEGS R. THE FO, WHO WAS THE PF, DID AN EXCELLENT JOB OF MAINTAINING POSITIVE CTL OF THE ACFT WITHOUT RADICAL CTL OR THROTTLE INPUT. THE DURATION OF THE ENCOUNTER WAS LESS THAN 5 SECONDS. WE RETURNED TO FL390. THE AIR ON THE OTHER SIDE WAS CLR WITH FAIRLY GOOD VISIBILITY AND SMOOTH. IT CONTINUED SMOOTH FOR THE DURATION OF THE FLT. WE RPTED SEVERE TURB TO ATC. I CHKED WITH THE FLT ATTENDANTS TO SEE IF EVERYONE WAS OK. THE LEAD FLT ATTENDANT INDICATED THERE WERE SOME PEOPLE STANDING IN THE AISLE WHEN WE ENCOUNTERED THE TURB AND THERE WERE SOME INJURIES AND THAT THEY WERE TENDING TO THEM. I REQUESTED A CALL BACK WITH MORE INFO AND THE SEVERITY OF THE INJURIES WHEN ABLE. I CALLED BACK IN A FEW MINS TO DETERMINE EXTENT OF INJURIES. SHE INDICATED SOME PAIN, BRUISES, CUTS (4-5 PAX). SHE INDICATED 1 PAX WAS IN THE LAVATORY AT THE TIME OF THE TURB. I ASKED HER OPINION IF EXTENT OF INJURIES WERE SERIOUS ENOUGH TO WARRANT A DIVERT. SHE SAID SHE DIDN'T THINK SO, AND INDICATED THE SIT WAS STABILIZED. (WE WERE ABOUT 25 MINS OUT OF ZZZ.) I CONFERRED WITH THE FO AND WE AGREED DIVERSION WAS UNNECESSARY AS TO OUR CLOSE PROX TO ZZZ. WE DECLARED AN EMER WITH INJURIES ON BOARD. WE WERE CLRED DIRECT ZZZ. I CALLED DISPATCH ON THE AIR PHONE AND ADVISED THEM OF SIT, AND REQUESTED PARAMEDICS MEET THE ACFT AT GATE, AND A CUSTOMER SVC SUPVR. I CHKED WITH THE FLT ATTENDANTS AGAIN AS TO STATUS OF PAX AND CREW. THEY INDICATED PAX HAVE ICE PACKS. NOSE INJURY TO 1 PAX, POSSIBLE CUTS, BRUISES, ETC. I CONTACTED OPS AND VERIFIED PARAMEDICS TO MEET THE ACFT. LANDED WITHOUT FURTHER INCIDENT. PARAMEDICS MET ACFT AND ATTENDED TO PAX. WE TALKED TO MAINT AT THE GATE FOR LOGBOOK WRITE-UP AND AGAIN LATER BY PHONE. OVERALL, THE TURB ENCOUNTER WAS UNAVOIDABLE, AND RECOVERY AND CTL OF THE EVENT WAS EXCELLENT. OUR MAIN OBJECTIVE WAS CTL OF THE ACFT, ASSESS THE SIT, AND COORDINATE THE RESPONSE. THE FLT ATTENDANTS DID AN EXCELLENT JOB CARING FOR THE PAX AND STABILIZING THE SIT. THE COM WITH ME WAS EXCELLENT. THE COORD WITH ATC AND DISPATCH ALSO WENT VERY WELL AND ALL SVCS MET US PROMPTLY.

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.