An CAA incident report documents 2 Dash-8-100 pilots letting the speed drop from 170 to 104 kts climing after departure, while they was picking up ice at the same time.
Then the stick shaker activated, the autopilot turned off, they fell 4,200 feet. they stalled 3 separate times and finally recovered. They continued to their destination where they reported a "turbulence event."
Oops.
Looks like they might have been using VS in the climb instead of IAS.