Citation C525 crew has fumes in cockpit and cabin; declares an emergency and lands.

Attributes
ACN	710490
Time
Date	200609
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 33000
Environment
Flight Conditions	IMC IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	general aviation : corporate
Make Model Name	Cessna Citation Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : multi engine
Experience	flight time last 90 days : 113 flight time total : 7600 flight time type : 246
ASRS Report	710490
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	aircraft equipment other aircraft equipment : air duct overheat light other flight crewa other flight crewb
Resolutory Action	aircraft : evacuated controller : provided flight assist flight crew : landed as precaution flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Descending through FL330 the 'air duct overheat' caution light illuminated. The appropriate checklist was run but had no effect on correcting the problem. The cabin and cockpit were soon enveloped by a strong; acrid; burning odor at which time we declared an emergency and executed a rapid descent while requesting the closest airport. ATC vectored us to an ILS approach at ZZZ. We landed the aircraft and evacuate/evacuationed by normal egress without further incident.

Original NASA ASRS Text

Title: CITATION C525 CREW HAS FUMES IN COCKPIT AND CABIN; DECLARES AN EMER AND LANDS.

Narrative: DSNDING THROUGH FL330 THE 'AIR DUCT OVERHEAT' CAUTION LIGHT ILLUMINATED. THE APPROPRIATE CHKLIST WAS RUN BUT HAD NO EFFECT ON CORRECTING THE PROB. THE CABIN AND COCKPIT WERE SOON ENVELOPED BY A STRONG; ACRID; BURNING ODOR AT WHICH TIME WE DECLARED AN EMER AND EXECUTED A RAPID DSCNT WHILE REQUESTING THE CLOSEST ARPT. ATC VECTORED US TO AN ILS APCH AT ZZZ. WE LANDED THE ACFT AND EVACED BY NORMAL EGRESS WITHOUT FURTHER INCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 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.