ATR42 crew had an altitude deviation in tjcs class east.

Attributes
ACN	511520
Time
Date	200105
Day	Tue
Place
Locale Reference	intersection : slugo
State Reference	VI
Altitude	msl bound lower : 11000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	ATR 42
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 120 flight time total : 3350 flight time type : 1660
ASRS Report	511520
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter other non adherence : far non adherence : company policies non adherence : published procedure non adherence : clearance other anomaly other
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Weather
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on route from tupj to st. Martin, netherlands, antilles. We leveled off at 11000 ft qne and performed cruise checks. I was PNF. Center advised us to cross slugo intersection at 9000 ft qne. I then went to adjust our WX radar for some cumulus build ups ahead. During this time the PF decided to start descent for 9000 ft. We selected 9000 ft and I went back to the radar. When I finished I discovered the altimeter was reading almost 12000 ft. I feel the contributing factor to this was that the PNF selected the wrong vertical speed mode and the aircraft began to climb slowly. My corrective action was to immediately begin descent towards 11000 ft.

Original NASA ASRS Text

Title: ATR42 CREW HAD AN ALTDEV IN TJCS CLASS E.

Narrative: WE WERE ON RTE FROM TUPJ TO ST. MARTIN, NETHERLANDS, ANTILLES. WE LEVELED OFF AT 11000 FT QNE AND PERFORMED CRUISE CHKS. I WAS PNF. CTR ADVISED US TO CROSS SLUGO INTXN AT 9000 FT QNE. I THEN WENT TO ADJUST OUR WX RADAR FOR SOME CUMULUS BUILD UPS AHEAD. DURING THIS TIME THE PF DECIDED TO START DSCNT FOR 9000 FT. WE SELECTED 9000 FT AND I WENT BACK TO THE RADAR. WHEN I FINISHED I DISCOVERED THE ALTIMETER WAS READING ALMOST 12000 FT. I FEEL THE CONTRIBUTING FACTOR TO THIS WAS THAT THE PNF SELECTED THE WRONG VERT SPD MODE AND THE ACFT BEGAN TO CLB SLOWLY. MY CORRECTIVE ACTION WAS TO IMMEDIATELY BEGIN DSCNT TOWARDS 11000 FT.

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.