Narrative:

Encountered severe turbulence in clear air during climb to cruise altitude; beginning about 14000 ft MSL and continuing through about FL180. I was PF. Autoplt/command steering engaged; at climb thrust and FMS computed economy climb speed of 330 KIAS. Ride conditions were completely smooth prior to encounter. Aircraft 'bunted' over slightly and began to accelerate; followed quickly by turbulence onset (I initially thought I had encountered wake turbulence; then thought it was mach buffet; as the climb speed was close to vmo; and was increasing during the initial part of the encounter). Intensity very quickly increased to severe conditions; with the mach warning tone (clacker) sounding; all in rapid succession. Airspeed exceeded vmo by about 10 KTS (estimate top speed 325 KIAS). I disengaged the autoplt; then decreased power and began to increase pitch to bring airspeed down to 280 KIAS (turbulent air penetration speed). I selected PA on the communication panel and directed the flight attendants to be seated. Aircraft continued to pitch and roll significantly; with notable excursions in positive and negative G loads (about 0 to 2.5). We had been cleared to climb to FL230; and I was able to control the climb rate and general flight parameters shortly after passing FL180. I called for altimeter setting 29.92 and re-engaged the autoplt about FL210. Turbulence diminished to 'light' by FL200 and continued through about FL250. I determined the aircraft was flyable and responding normally; with normal cockpit indications. I then called the flight attendants on the service interphone to check their status. They were ok; but the 'B' flight attendant told me he had hit his back on something and in slight pain; otherwise was ok. They told me all passenger had been seated/buckled in; and no damage or injuries had occurred. We advised ATC of the encounter shortly after leaving FL180. There had been no mention made of any adverse ride conditions by ATC; and they said our report was the first adverse report they had heard in the area.

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Original NASA ASRS Text

Title: B737-300 FLT CREW ENCOUNTERS SEVERE TURB DURING CLB TO ALT. VMO EXCEEDED; ACFT PITCHED UP.

Narrative: ENCOUNTERED SEVERE TURB IN CLR AIR DURING CLB TO CRUISE ALT; BEGINNING ABOUT 14000 FT MSL AND CONTINUING THROUGH ABOUT FL180. I WAS PF. AUTOPLT/COMMAND STEERING ENGAGED; AT CLB THRUST AND FMS COMPUTED ECONOMY CLB SPD OF 330 KIAS. RIDE CONDITIONS WERE COMPLETELY SMOOTH PRIOR TO ENCOUNTER. ACFT 'BUNTED' OVER SLIGHTLY AND BEGAN TO ACCELERATE; FOLLOWED QUICKLY BY TURB ONSET (I INITIALLY THOUGHT I HAD ENCOUNTERED WAKE TURB; THEN THOUGHT IT WAS MACH BUFFET; AS THE CLB SPD WAS CLOSE TO VMO; AND WAS INCREASING DURING THE INITIAL PART OF THE ENCOUNTER). INTENSITY VERY QUICKLY INCREASED TO SEVERE CONDITIONS; WITH THE MACH WARNING TONE (CLACKER) SOUNDING; ALL IN RAPID SUCCESSION. AIRSPD EXCEEDED VMO BY ABOUT 10 KTS (ESTIMATE TOP SPD 325 KIAS). I DISENGAGED THE AUTOPLT; THEN DECREASED PWR AND BEGAN TO INCREASE PITCH TO BRING AIRSPD DOWN TO 280 KIAS (TURBULENT AIR PENETRATION SPD). I SELECTED PA ON THE COM PANEL AND DIRECTED THE FLT ATTENDANTS TO BE SEATED. ACFT CONTINUED TO PITCH AND ROLL SIGNIFICANTLY; WITH NOTABLE EXCURSIONS IN POSITIVE AND NEGATIVE G LOADS (ABOUT 0 TO 2.5). WE HAD BEEN CLRED TO CLB TO FL230; AND I WAS ABLE TO CTL THE CLB RATE AND GENERAL FLT PARAMETERS SHORTLY AFTER PASSING FL180. I CALLED FOR ALTIMETER SETTING 29.92 AND RE-ENGAGED THE AUTOPLT ABOUT FL210. TURB DIMINISHED TO 'LIGHT' BY FL200 AND CONTINUED THROUGH ABOUT FL250. I DETERMINED THE ACFT WAS FLYABLE AND RESPONDING NORMALLY; WITH NORMAL COCKPIT INDICATIONS. I THEN CALLED THE FLT ATTENDANTS ON THE SVC INTERPHONE TO CHK THEIR STATUS. THEY WERE OK; BUT THE 'B' FLT ATTENDANT TOLD ME HE HAD HIT HIS BACK ON SOMETHING AND IN SLIGHT PAIN; OTHERWISE WAS OK. THEY TOLD ME ALL PAX HAD BEEN SEATED/BUCKLED IN; AND NO DAMAGE OR INJURIES HAD OCCURRED. WE ADVISED ATC OF THE ENCOUNTER SHORTLY AFTER LEAVING FL180. THERE HAD BEEN NO MENTION MADE OF ANY ADVERSE RIDE CONDITIONS BY ATC; AND THEY SAID OUR RPT WAS THE FIRST ADVERSE RPT THEY HAD HEARD IN THE AREA.

Data retrieved from NASA's ASRS site as of January 2009 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.