Commuter small transport enroute WX encounter causing altitude excursion.

Attributes
ACN	106139
Time
Date	198903
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fra
State Reference	CA
Altitude	msl bound lower : 12200 msl bound upper : 16000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 60 flight time total : 2500 flight time type : 35
ASRS Report	106139
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 60 flight time total : 1500
ASRS Report	106133
Events
Anomaly	altitude deviation : undershoot inflight encounter : weather inflight encounter other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

Due to violent up- and downdrafts we lost considerable altitude (over 2000'). There was moderate icing, and some foreign object caused a hole through pilot's side of the forward window. Minimum safe altitude was regained and we continued to bishop with one engine temporarily running rough.

Original NASA ASRS Text

Title: COMMUTER SMT ENROUTE WX ENCOUNTER CAUSING ALT EXCURSION.

Narrative: DUE TO VIOLENT UP- AND DOWNDRAFTS WE LOST CONSIDERABLE ALT (OVER 2000'). THERE WAS MODERATE ICING, AND SOME FOREIGN OBJECT CAUSED A HOLE THROUGH PLT'S SIDE OF THE FORWARD WINDOW. MINIMUM SAFE ALT WAS REGAINED AND WE CONTINUED TO BISHOP WITH ONE ENG TEMPORARILY RUNNING ROUGH.

Data retrieved from NASA's ASRS site as of August 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.