Narrative:

In cruise flight at FL200. I was the pilot monitoring; the first officer was the pilot flying. Flight condition at the time of the incident was IMC; light occasional moderate icing with a temp -9C. (I had just made a PIREP). We experienced a momentary activation of the stick shaker. It went away within 5 sec; the autopilot was disconnected and the first officer proceeded to hand fly. We then requested a climb to FL220 where we thought we might be able to get on top. ATC gave us a climb to FL220. After we broke out of the clouds at FL210 and continued our climb to FL220. I then let the flight attendant serve the passengers (we had 10 passengers). While at FL220 we discussed what might have caused the activation of the stick shaker. We mentioned the icing and discussed personal experiences related to our situation. I also looked through the abnormal checklist for guidance on stick shaker activation and did not find a checklist or group of checklist that met our situation. We were satisfied that exiting the icing conditions was our safest course of action; which we had already done. We determined at this time that due to the short duration of the activation it was most likely an anomaly and that I would call maintenance. When center issued us a descent to 16000 I asked the flight attendant to sit back down. As we passed through FL200 the stick shaker reactivated and remained on. Not knowing whether we had an actual problem or not we elected to declare an emergency and land as soon as possible. I asked ATC for vectors to the nearest airport which was 40 miles to our east and requested the ILS. I called the flight attendant on the emergency call button. (Note: during this flight the flight attendant call button was intermittent and we had tested the emergency call button while trouble shooting what might be wrong with the system so I could make an effective write up). I told the flight attendant that we were declaring an emergency and diverting. I also told her that we had stick shaker activation and that I was unsure how serious the problem was but that the safest course of action was to prepare the passengers for the brace position and that we would be on the ground in approx 10 minutes. I attempted to call operations on the #2 radio and was unsuccessful in reaching them. I told ATC that I would like them to call the company for us. At approximately 10;000 ft I told ATC that I would like to maneuver for a moment. I took control from the first officer and slowed to 160 KTS. Aside from the stick shaker going off the controls felt normal and I was confident that we would be able to land the aircraft without exceeding limitations and that most likely this was a system malfunction. We did however treat the aircraft as if we had a serious flight control malfunction and briefed it as such. (At this point the ice had melted from the wings and I did not feel that a zero flap landing was necessary to prevent a change in angle of attack on final). I returned the control of the aircraft to the first officer. I then resumed my pilot not flying duties and ran the descent approach checklist. I advised ATC that we would like the equipment to follow us and told the flight attendant that I would issue the brace command at 500 ft. As we were being vectored onto the approach (the stick shaker is still active) I continued to look for a circuit breaker labeled stick shaker. I then proceeded to unplug the cannon plug from my shaker it did not stop the activation. As I tried to unplug the first officer's cannon plug the activation finally stopped. We continued on the ILS as briefed and at 500 ft I issued the brace command. We had a normal landing and taxied to the gate.

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Original NASA ASRS Text

Title: A DHC-8-100 stall warning activated momentarily in cruise icing conditions. After climbing clear of clouds at FL220 a descent was begun for landing. The stall warning activated again in the clouds during the descent but ceased after diverting to a nearby airport.

Narrative: In cruise flight at FL200. I was the pilot monitoring; the First Officer was the pilot flying. Flight condition at the time of the incident was IMC; light occasional moderate icing with a temp -9C. (I had just made a PIREP). We experienced a momentary activation of the stick shaker. It went away within 5 sec; the autopilot was disconnected and the First Officer proceeded to hand fly. We then requested a climb to FL220 where we thought we might be able to get on top. ATC gave us a climb to FL220. After we broke out of the clouds at FL210 and continued our climb to FL220. I then let the Flight Attendant serve the passengers (we had 10 passengers). While at FL220 we discussed what might have caused the activation of the stick shaker. We mentioned the icing and discussed personal experiences related to our situation. I also looked through the abnormal checklist for guidance on stick shaker activation and did not find a checklist or group of checklist that met our situation. We were satisfied that exiting the icing conditions was our safest course of action; which we had already done. We determined at this time that due to the short duration of the activation it was most likely an anomaly and that I would call Maintenance. When Center issued us a descent to 16000 I asked the Flight Attendant to sit back down. As we passed through FL200 the stick shaker reactivated and remained on. Not knowing whether we had an actual problem or not we elected to declare an emergency and land as soon as possible. I asked ATC for vectors to the nearest airport which was 40 miles to our east and requested the ILS. I called the Flight Attendant on the EMERGENCY CALL button. (Note: During this flight the Flight Attendant CALL button was intermittent and we had tested the EMERGENCY CALL button while trouble shooting what might be wrong with the system so I could make an effective write up). I told the Flight Attendant that we were declaring an emergency and diverting. I also told her that we had stick shaker activation and that I was unsure how serious the problem was but that the safest course of action was to prepare the passengers for the brace position and that we would be on the ground in approx 10 minutes. I attempted to call Operations on the #2 radio and was unsuccessful in reaching them. I told ATC that I would like them to call the company for us. At approximately 10;000 FT I told ATC that I would like to maneuver for a moment. I took control from the First Officer and slowed to 160 KTS. Aside from the stick shaker going off the controls felt normal and I was confident that we would be able to land the aircraft without exceeding limitations and that most likely this was a system malfunction. We did however treat the aircraft as if we had a serious flight control malfunction and briefed it as such. (At this point the ice had melted from the wings and I did not feel that a zero flap landing was necessary to prevent a change in angle of attack on final). I returned the control of the aircraft to the First Officer. I then resumed my pilot not flying duties and ran the descent approach checklist. I advised ATC that we would like the equipment to follow us and told the Flight Attendant that I would issue the brace command at 500 FT. As we were being vectored onto the approach (the stick shaker is still active) I continued to look for a circuit breaker labeled stick shaker. I then proceeded to unplug the cannon plug from my shaker it did not stop the activation. As I tried to unplug the First Officer's cannon plug the activation finally stopped. We continued on the ILS as briefed and at 500 FT I issued the brace command. We had a normal landing and taxied to the gate.

Data retrieved from NASA's ASRS site as of April 2012 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.