A B757-200 lost 300 ft at FL350 following after encountering strong moderate turbulence near a build...

Attributes
ACN	1101888
Time
Date	201307
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	Marginal
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Total 23000
Person 2
Function	Pilot Flying First Officer
Experience	Flight Crew Total 6000
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence

Narrative:

Encountered strong moderate turbulence associated with smaller thunderstorm activity over the caribbean. With autopilot on; aircraft descended approximately 300 ft below FL350 with rapidly increasing airspeed. Disconnected autopilot and autothrottles and returned to FL350. Reengaged autopilot. Called cabin to check for possible injuries. None. Reported altitude deviation to center. Center reported no deviation shown. Reported turbulence to dispatch. Proceeded to destination uneventfully.although already cleared and executing deviation for weather around lighter returns; a wider deviation may have prevented occurrence.

Original NASA ASRS Text

Title: A B757-200 lost 300 FT at FL350 following after encountering strong moderate turbulence near a building thunderstorm which the crew attempted to avoid over the Caribbean.

Narrative: Encountered strong moderate turbulence associated with smaller thunderstorm activity over the Caribbean. With autopilot on; aircraft descended approximately 300 FT below FL350 with rapidly increasing airspeed. Disconnected autopilot and autothrottles and returned to FL350. Reengaged autopilot. Called cabin to check for possible injuries. None. Reported altitude deviation to Center. Center reported no deviation shown. Reported turbulence to Dispatch. Proceeded to destination uneventfully.Although already cleared and executing deviation for weather around lighter returns; a wider deviation may have prevented occurrence.

Data retrieved from NASA's ASRS site as of July 2013 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.

A B757-200 lost 300 ft at FL350 following after encountering strong moderate turbulence near a building thunderstorm which the crew attempted to avoid over the caribbean.