Narrative:

While flying through an area of thunderstorm -- light chop (on a heading to deviate around radar returns on buildups) FL390, api on, aircraft encountered a pronounced windshear and accelerated instantaneously into overspd protection mode. The nose pitched (autoplt disengaged) and plane started climbing. Captain initial inputs to sidestick (down) resulted in little or no effect. At FL401, control was regained (out of overspd protection mode) and plane started down a downdraft was encountered and plane descended to FL385 (approximately). Upon clearing shear area, altitude was recovered normally. ATC immediately (and alertly) assigned flight a block FL390-410 during deviation and was advised of moderate turbulence conditions and that a captain's safety report would be filed. (It was.) ATC was aware and helpful throughout event. Until area of unstable air was cleared, aircraft was in continuous moderate turbulence throughout encounter. Obvious conclusion would be to give wide birth to thunderstorm painting green-yellow at high altitudes. If it is anticipated or suspected that an area of moderate turbulence is about to be entered, turbulence penetration speed (.75 in A320) should be set. Passenger were already strapped in, seat belt light 'on' and flight attendants were told over PA to take their seats immediately at first jolt. No injures occurred. Callback conversation with reporter revealed the following: severe updraft in windshear from being too close to thunderstorms and penetrating cold front. Cruise speed .80 at high altitude allows small margin for abrupt airspeed increase and aircraft had overspd. Overspd protection activated which automatically disconnected the autoplt, autothrottles went to idle and sidestick (elevator) authority/authorized was reduced. Aircraft pitched up 5 degrees and aircraft in updraft climbed 1500 FPM. Reporter captain tried to push nose over, but with reduced stick authority/authorized, didn't push hard enough. When airspeed decreased, which did quite rapidly, the protection mode deactivated and captain regained elevator control. As aircraft was descending back to assigned altitude, the airspeed slowed enough to put aircraft into low speed protection area. Then, when trying to level at assigned altitude, the speed was too slow so the automatic protection would not allow nose up input. When airspeed increased, complete control was regained. The reporter captain states that had he used manual throttles and used toga thrust, the recovery would have been quicker. Also, had he been more aggressive with sidestick control, would have added to a faster recovery. Reporter would have allowed greater distance from thunderstorms and cruise at slower speed when in areas of possible turbulence and thunderstorms.

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Original NASA ASRS Text

Title: WINDSHEAR. ALTDEV. ACFT OVERSPD AND AUTOMATIC PROTECTION MODES ACTIVATED.

Narrative: WHILE FLYING THROUGH AN AREA OF TSTM -- LIGHT CHOP (ON A HDG TO DEVIATE AROUND RADAR RETURNS ON BUILDUPS) FL390, API ON, ACFT ENCOUNTERED A PRONOUNCED WINDSHEAR AND ACCELERATED INSTANTANEOUSLY INTO OVERSPD PROTECTION MODE. THE NOSE PITCHED (AUTOPLT DISENGAGED) AND PLANE STARTED CLBING. CAPT INITIAL INPUTS TO SIDESTICK (DOWN) RESULTED IN LITTLE OR NO EFFECT. AT FL401, CTL WAS REGAINED (OUT OF OVERSPD PROTECTION MODE) AND PLANE STARTED DOWN A DOWNDRAFT WAS ENCOUNTERED AND PLANE DSNDED TO FL385 (APPROX). UPON CLRING SHEAR AREA, ALT WAS RECOVERED NORMALLY. ATC IMMEDIATELY (AND ALERTLY) ASSIGNED FLT A BLOCK FL390-410 DURING DEV AND WAS ADVISED OF MODERATE TURB CONDITIONS AND THAT A CAPT'S SAFETY RPT WOULD BE FILED. (IT WAS.) ATC WAS AWARE AND HELPFUL THROUGHOUT EVENT. UNTIL AREA OF UNSTABLE AIR WAS CLRED, ACFT WAS IN CONTINUOUS MODERATE TURB THROUGHOUT ENCOUNTER. OBVIOUS CONCLUSION WOULD BE TO GIVE WIDE BIRTH TO TSTM PAINTING GREEN-YELLOW AT HIGH ALTS. IF IT IS ANTICIPATED OR SUSPECTED THAT AN AREA OF MODERATE TURB IS ABOUT TO BE ENTERED, TURB PENETRATION SPD (.75 IN A320) SHOULD BE SET. PAX WERE ALREADY STRAPPED IN, SEAT BELT LIGHT 'ON' AND FLT ATTENDANTS WERE TOLD OVER PA TO TAKE THEIR SEATS IMMEDIATELY AT FIRST JOLT. NO INJURES OCCURRED. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: SEVERE UPDRAFT IN WINDSHEAR FROM BEING TOO CLOSE TO TSTMS AND PENETRATING COLD FRONT. CRUISE SPD .80 AT HIGH ALT ALLOWS SMALL MARGIN FOR ABRUPT AIRSPD INCREASE AND ACFT HAD OVERSPD. OVERSPD PROTECTION ACTIVATED WHICH AUTOMATICALLY DISCONNECTED THE AUTOPLT, AUTOTHROTTLES WENT TO IDLE AND SIDESTICK (ELEVATOR) AUTH WAS REDUCED. ACFT PITCHED UP 5 DEGS AND ACFT IN UPDRAFT CLBED 1500 FPM. RPTR CAPT TRIED TO PUSH NOSE OVER, BUT WITH REDUCED STICK AUTH, DIDN'T PUSH HARD ENOUGH. WHEN AIRSPD DECREASED, WHICH DID QUITE RAPIDLY, THE PROTECTION MODE DEACTIVATED AND CAPT REGAINED ELEVATOR CTL. AS ACFT WAS DSNDING BACK TO ASSIGNED ALT, THE AIRSPD SLOWED ENOUGH TO PUT ACFT INTO LOW SPD PROTECTION AREA. THEN, WHEN TRYING TO LEVEL AT ASSIGNED ALT, THE SPD WAS TOO SLOW SO THE AUTO PROTECTION WOULD NOT ALLOW NOSE UP INPUT. WHEN AIRSPD INCREASED, COMPLETE CTL WAS REGAINED. THE RPTR CAPT STATES THAT HAD HE USED MANUAL THROTTLES AND USED TOGA THRUST, THE RECOVERY WOULD HAVE BEEN QUICKER. ALSO, HAD HE BEEN MORE AGGRESSIVE WITH SIDESTICK CTL, WOULD HAVE ADDED TO A FASTER RECOVERY. RPTR WOULD HAVE ALLOWED GREATER DISTANCE FROM TSTMS AND CRUISE AT SLOWER SPD WHEN IN AREAS OF POSSIBLE TURB AND TSTMS.

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.