Narrative:

Smoke in cockpit. Emergency declared with center and proceeded direct to ZZZ. Checklist accomplished and smoke stopped coming into cockpit. Supplemental information from acn 690380: in descent passing FL200; both pilots noticed 'hot' smell in cockpit. No abnormal instruments. Shortly after; I noticed smoke coming from under instrument panel; center pedestal. Donned masks; declared ife. Ran smoke in cockpit checklist. Smoke dissipated after turning off GPWS/WX panel; smell persisted. Decided to land ZZZ due to familiarity with field and solid undercast covering any other possible airfields.

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Original NASA ASRS Text

Title: B737-300 FLT CREW HAS SMOKE IN COCKPIT; EMER DECLARED.

Narrative: SMOKE IN COCKPIT. EMER DECLARED WITH CTR AND PROCEEDED DIRECT TO ZZZ. CHKLIST ACCOMPLISHED AND SMOKE STOPPED COMING INTO COCKPIT. SUPPLEMENTAL INFO FROM ACN 690380: IN DSCNT PASSING FL200; BOTH PLTS NOTICED 'HOT' SMELL IN COCKPIT. NO ABNORMAL INSTS. SHORTLY AFTER; I NOTICED SMOKE COMING FROM UNDER INST PANEL; CTR PEDESTAL. DONNED MASKS; DECLARED IFE. RAN SMOKE IN COCKPIT CHKLIST. SMOKE DISSIPATED AFTER TURNING OFF GPWS/WX PANEL; SMELL PERSISTED. DECIDED TO LAND ZZZ DUE TO FAMILIARITY WITH FIELD AND SOLID UNDERCAST COVERING ANY OTHER POSSIBLE AIRFIELDS.

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.