Dash 8-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
We were at FL210 when we noticed the master caution light illuminate as well as the AUX INVERT light. I called for the checklist for this light. We were starting a descent at this point and after a minute or two of running through the checklist we noticed a faint odor that smelled electrical or like burnt plastic. We told ATC about it and I requested to continue our descent in case the odor increased. We continued the checklist for the AUX INVERT light while we continued our descent to 7;000 FT. The odor got continuously worse so I had the First Officer don his oxygen mask and I did the same. At this point we declared an emergency and requested to land as soon as practical. ATC advised us that ZZZ was very close so we decided to divert there. We ran the checklist for smoke in the cockpit even though there wasn't any visible smoke. I quickly notified the Flight Attendant about the emergency and to prepare the cabin for a normal arrival and that we would be on the ground in five minutes. We did not have enough time to call Dispatch to inform them because ATC vectored us right onto a six mile final and we landed without incident. The fire truck was waiting and followed us in to the ramp where we shut down.
A DHC8-200 AUX INVERT light displayed at FL210 followed shortly by the smell of an overheated electrical component. The emergency checklist was used and the flight diverted to the nearest suitable airport.