Flight Crew Air Transport Pilot (ATP)
Time Pressure; Physiological - Other
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Inflight Event / Encounter Weather / Turbulence
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Evacuated; General Flight Cancelled / Delayed; General Declared Emergency
Aircraft
The flight had progressed normally through challenging conditions that included light to moderate turbulence and icing through areas of embedded shower activity. While enroute we began a descent from FL190 due to icing conditions at altitude. At this point we detected a strange odor that was accompanied by a blue haze on the flight deck. The Flight Attendant advised the same conditions were developing in the passenger cabin. An emergency condition was immediately declared with Center with the intention of diverting to a nearby airport. The flight was immediately cleared direct to the airport; descend to 4;000 feet. During the descent; all checklist items were completed; passengers were briefed; Operations and ATC were notified of the plan to land and stop on the runway for further evaluation of the situation. As Pilot Flying; I had suited up my oxygen mask and communicated with ATC while the PIC consulted with the Flight Attendant and Company Operations. After being handed to Approach Control; the flight was cleared for an ILS approach to Runway XX. Tracking the localizer inbound; all checklist items were completed and a normal landing was completed. Once on the ground; the aircraft was brought to a complete stop. Emergency crews standing by then evaluated the aircraft and gave a thumbs up indication. As it was being determined that the aircraft could be taxied; the Flight Attendant advised the Captain that the smoke conditions in the cabin had not ceased. The Captain then ordered an evacuation. The Captain shut down the engines; and then went to assist the Flight Attendant in directing our passengers out the airstair exit. I advised ATC that we were evacuating the aircraft on the runway and I completed the emergency checklist as the rest of the passengers exited the aircraft. I then consulted with the Captain; he indicating all passengers were off the aircraft and I advising him that the aircraft was fully depowered. We then exited the aircraft and joined the emergency ground crews outside the aircraft.
Later the Flight Attendant found out that we were on the news all ready; even while we were on the runway. Then she advised me that another Flight Attendant had reported the same thing weeks before. Later I even found out that we might have had another event. That makes four. Pushing to fly or ferry broken aircraft without any correct checkout is still a problem that needs to be addressed!
When the DHC-8 flight crew and Flight Attendant all detected strange odors and haze the flight diverted to a nearby airport.  After landing the Flight Attendant advised the conditions in the cabin were unchanged the Captain ordered an evacuation.