Could not maintain assigned altitude because of severe icing.

Attributes
ACN	287844
Time
Date	199411
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lch
State Reference	LA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	SF 340A
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute airway : zhu
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 6200 flight time type : 350
ASRS Report	287844
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather other anomaly other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	aircraft : equipment problem dissipated flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Aircraft loaded up with ice and the airspeed decreased until the stick shaker went off. 600 ft was lost to maintain airspeed. Callback conversation with reporter revealed the following information: aircraft was saab 340A with the dowty rotol composite propeller. There was no problem with the icing equipment, however, talking to other pilots, this has happened before. Reporter usually flies the model with the hamilton standard propellers and this has not happened before. Did not declare an emergency. The airplane was under control except within a matter of seconds the speed went from an indicated 190-140, the autoplt kicked off alerting them to the problem, then the stick shaker, and that lowered the nose with maximum power, the first officer who is also a captain notified center of the severe icing and requested a lower altitude which was immediately given, but by that time, they were 600 ft lower and breaking out of the clouds at about 18400 ft, and were cleared then to 17000 ft. The icing equipment was on and the boots seemed to be doing the job of de-icing the wings normally. The airport saw ice build up on the wing and turned on the boots and the ice would shed. They were being rted because of WX around thunderstorms that were north of them. The icing was not a wing problem, or an engine power problem, but rather, seemed to be a propeller efficiency loss problem.

Original NASA ASRS Text

Title: COULD NOT MAINTAIN ASSIGNED ALT BECAUSE OF SEVERE ICING.

Narrative: ACFT LOADED UP WITH ICE AND THE AIRSPD DECREASED UNTIL THE STICK SHAKER WENT OFF. 600 FT WAS LOST TO MAINTAIN AIRSPD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: ACFT WAS SAAB 340A WITH THE DOWTY ROTOL COMPOSITE PROP. THERE WAS NO PROB WITH THE ICING EQUIP, HOWEVER, TALKING TO OTHER PLTS, THIS HAS HAPPENED BEFORE. RPTR USUALLY FLIES THE MODEL WITH THE HAMILTON STANDARD PROPS AND THIS HAS NOT HAPPENED BEFORE. DID NOT DECLARE AN EMER. THE AIRPLANE WAS UNDER CTL EXCEPT WITHIN A MATTER OF SECONDS THE SPD WENT FROM AN INDICATED 190-140, THE AUTOPLT KICKED OFF ALERTING THEM TO THE PROB, THEN THE STICK SHAKER, AND THAT LOWERED THE NOSE WITH MAX PWR, THE FO WHO IS ALSO A CAPT NOTIFIED CTR OF THE SEVERE ICING AND REQUESTED A LOWER ALT WHICH WAS IMMEDIATELY GIVEN, BUT BY THAT TIME, THEY WERE 600 FT LOWER AND BREAKING OUT OF THE CLOUDS AT ABOUT 18400 FT, AND WERE CLRED THEN TO 17000 FT. THE ICING EQUIP WAS ON AND THE BOOTS SEEMED TO BE DOING THE JOB OF DE-ICING THE WINGS NORMALLY. THE ARPT SAW ICE BUILD UP ON THE WING AND TURNED ON THE BOOTS AND THE ICE WOULD SHED. THEY WERE BEING RTED BECAUSE OF WX AROUND TSTMS THAT WERE N OF THEM. THE ICING WAS NOT A WING PROB, OR AN ENG PWR PROB, BUT RATHER, SEEMED TO BE A PROP EFFICIENCY LOSS PROB.

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.