Captain of an MD90 temporarily lost aircraft control when entering thunderstorm turbulence during cruise. Encounter resulted in loss and gain of altitude and airspeed, but no injuries.

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Attributes
ACN	473979
Time
Date	200005
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : ilc.vortac
Altitude	msl bound lower : 28500 msl bound upper : 29500
Environment
Flight Conditions	Mixed
Weather Elements	Thunderstorm Rain Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	MD-90 Series (DC-9-90) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : j80.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier company other government : faa government other other Other
Function	observation : air carrier inspector oversight : pic
ASRS Report	473979
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 13000 flight time type : 5000
ASRS Report	473980
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter : turbulence other anomaly
Independent Detector	aircraft equipment other aircraft equipment : airspeed / actimeter other flight crewa other flight crewb
Resolutory Action	flight crew : regained aircraft control flight crew : returned to assigned altitude other
Consequence	Other
Supplementary
Problem Areas	Flight Crew Human Performance Weather
Primary Problem	Weather

Narrative:

While in cruise at FL290, encountered a band/area of rapidly building thunderstorms. No government alerts (WX) and only metropolitan alert was for widely scattered thunderstorms. Initially attempted to deviate south but could not go far enough due to restr areas. Higher altitude was not available (ATC) and a northern deviation was choked off by the thunderstorms. During an attempt to get through what appeared (on WX radar) to be least threatening area, we encountered the top/leading edge of one of the rapidly building thunderstorms. We immediately had severe turbulence, very heavy rain, and associated airspeed and altitude gains and losses. Airspeed fluctuations approximately +/-30 KTS, altitude changes +/-500 ft. PF exercised all available options to get clear as soon as possible. Autoplt disconnected itself at the initial encounter and pilot hand flew the aircraft as smoothly as possible to clear air and a return to cruise airspeed and altitude. ATC notified of thunderstorms areas and information also passed to company dispatcher. No traffic conflicts, crew, or passenger injuries reported.

Original NASA ASRS Text

Title: CAPT OF AN MD90 TEMPORARILY LOST ACFT CTL WHEN ENTERING TSTM TURB DURING CRUISE. ENCOUNTER RESULTED IN LOSS AND GAIN OF ALT AND AIRSPD, BUT NO INJURIES.

Narrative: WHILE IN CRUISE AT FL290, ENCOUNTERED A BAND/AREA OF RAPIDLY BUILDING TSTMS. NO GOV ALERTS (WX) AND ONLY METRO ALERT WAS FOR WIDELY SCATTERED TSTMS. INITIALLY ATTEMPTED TO DEVIATE S BUT COULD NOT GO FAR ENOUGH DUE TO RESTR AREAS. HIGHER ALT WAS NOT AVAILABLE (ATC) AND A NORTHERN DEV WAS CHOKED OFF BY THE TSTMS. DURING AN ATTEMPT TO GET THROUGH WHAT APPEARED (ON WX RADAR) TO BE LEAST THREATENING AREA, WE ENCOUNTERED THE TOP/LEADING EDGE OF ONE OF THE RAPIDLY BUILDING TSTMS. WE IMMEDIATELY HAD SEVERE TURB, VERY HVY RAIN, AND ASSOCIATED AIRSPD AND ALT GAINS AND LOSSES. AIRSPD FLUCTUATIONS APPROX +/-30 KTS, ALT CHANGES +/-500 FT. PF EXERCISED ALL AVAILABLE OPTIONS TO GET CLR ASAP. AUTOPLT DISCONNECTED ITSELF AT THE INITIAL ENCOUNTER AND PLT HAND FLEW THE ACFT AS SMOOTHLY AS POSSIBLE TO CLR AIR AND A RETURN TO CRUISE AIRSPD AND ALT. ATC NOTIFIED OF TSTMS AREAS AND INFO ALSO PASSED TO COMPANY DISPATCHER. NO TFC CONFLICTS, CREW, OR PAX INJURIES RPTED.

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.