<< >> NASA ASRS Report 195988, December 1991

Commuter aircraft encounters icing. Unable to maintain altitude. Altitude excursion prior to descent clearance.

Attributes
ACN	195988
Time
Date	199112
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : sea
State Reference	WA
Altitude	msl bound lower : 9700 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : sea
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : instrument pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 4300 flight time type : 1800
ASRS Report	195988
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation other

Narrative:

We were in cruise, inbound to sea at 15 DME on sea 101 degree radial. We encountered moderate rime icing that built up to 1 inch. We were unable to maintain altitude to keep aircraft under control and lost 500 ft. As we descended through 200-300 ft below assigned altitude, I notified approach and we were cleared to 7000 ft. We had already popped our boots and were close to a usual descent gate. We descended on our own to maintain aircraft control as aircraft was beginning to want to roll and we had to keep airspeed up.

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Original NASA ASRS Text

Title: COMMUTER ACFT ENCOUNTERS ICING. UNABLE TO MAINTAIN ALT. ALT EXCURSION PRIOR TO DSCNT CLRNC.

Narrative: WE WERE IN CRUISE, INBOUND TO SEA AT 15 DME ON SEA 101 DEG RADIAL. WE ENCOUNTERED MODERATE RIME ICING THAT BUILT UP TO 1 INCH. WE WERE UNABLE TO MAINTAIN ALT TO KEEP ACFT UNDER CTL AND LOST 500 FT. AS WE DSNDED THROUGH 200-300 FT BELOW ASSIGNED ALT, I NOTIFIED APCH AND WE WERE CLRED TO 7000 FT. WE HAD ALREADY POPPED OUR BOOTS AND WERE CLOSE TO A USUAL DSCNT GATE. WE DSNDED ON OUR OWN TO MAINTAIN ACFT CTL AS ACFT WAS BEGINNING TO WANT TO ROLL AND WE HAD TO KEEP AIRSPD UP.

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.