Altitude deviation near msp when WX avoidance and vectoring were in progress.

Attributes
ACN	490220
Time
Date	200010
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : gep.vortac
State Reference	MN
Altitude	msl bound lower : 10600 msl bound upper : 11000
Environment
Flight Conditions	IMC
Weather Elements	Thunderstorm Rain Turbulence
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent : intermediate altitude
Route In Use	arrival star : gopher 4
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 8000 flight time type : 2600
ASRS Report	490220
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 10000
ASRS Report	489995
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Weather Flight Crew Human Performance Aircraft
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

While deviating around thunderstorms in turbulence and being asked to take 1 of 2 headings and the radar stabilization would be very poor during any amount of turn, descended 400-500 ft below altitude. Crew discovered and corrected. Supplemental information from acn 489995: first officer was flying. Captain retuned the radar and noticed the aircraft had descended to 10600 ft. Immediately brought to first officer's attention and he immediately corrected to 11000 ft and we were cleared to 7000 ft just as we were leveling off at 11000 ft. No conflict was experienced.

Original NASA ASRS Text

Title: ALTDEV NEAR MSP WHEN WX AVOIDANCE AND VECTORING WERE IN PROGRESS.

Narrative: WHILE DEVIATING AROUND TSTMS IN TURB AND BEING ASKED TO TAKE 1 OF 2 HDGS AND THE RADAR STABILIZATION WOULD BE VERY POOR DURING ANY AMOUNT OF TURN, DSNDED 400-500 FT BELOW ALT. CREW DISCOVERED AND CORRECTED. SUPPLEMENTAL INFO FROM ACN 489995: FO WAS FLYING. CAPT RETUNED THE RADAR AND NOTICED THE ACFT HAD DSNDED TO 10600 FT. IMMEDIATELY BROUGHT TO FO'S ATTN AND HE IMMEDIATELY CORRECTED TO 11000 FT AND WE WERE CLRED TO 7000 FT JUST AS WE WERE LEVELING OFF AT 11000 FT. NO CONFLICT WAS EXPERIENCED.

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.