UNAUTHORIZED PENETRATION OF AIRSPACE. PROX OF CTL ZONE.

Narrative

I DEPARTED FELTS FIELD IN SPOKANE ON A VFR FLT TO COE. BEFORE DEPARTING; I FAILED TO CHK WITH WX SVC FOR WX CONDITIONS AT COEUR D'ALENE ARPT. I BEGAN CALLING THE COE TWR ON 119.1 ABOUT 5 MI W OF THE FIELD BUT WAS UNABLE TO GET A RESPONSE. MY ALT WAS 3100 MSL AND VISIBILITY GOOD. AFTER REPEATED ATTEMPTS TO RAISE ANYONE ON EITHER 119.1 OR 122.8 I ENTERED A VFR DOWNWIND APCH ANNOUNCING MY INTENTIONS ON 119.1 AND 122.8. AS I WAS TURNING R BASE FOR RWY 1 I NOTICED AN LTT AIRLINER ON FINAL FOR THE SAME RWY. I THEN PROCEEDED WITH A GAR WELL CLR AND TO THE R OF THE APCH TO RWY 1. I WAS THEN ABLE TO GET SOMEONE ON 122.8 WHO ADVISED ME THAT THE ARPT WAS SHOWING AN 800 FT CEILING AND WAS UNDER IFR CONDITIONS. I IMMEDIATELY DEPARTED THE AREA AND RETURNED TO FELTS FIELD FOR LNDG. I INADVERTENTLY ENTERED CTLED IFR AIRSPACE WHILE FLYING VFR. I HAD NOT CHKED WITH WX SVC IN ADVANCE NOR HAD I LISTED TO THE LCL AWOS ON 135.075. THE VISIBILITY WAS GOOD AND THE CEILING APPEARED ADEQUATE SO I DID NOT EXPECT IFR CONDITIONS AT COE.