AN EMBRAER 145 IN CRUISE AT FL280 HAS WINDOW HEAT OFF. DSNDED THROUGH OVERCAST TO 4000 FT. ALL 4 COCKPIT WINDOWS FOGGED UP. VISION IMPAIRED.

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AT FL280 CLEAR SKIES; OVERCAST BELOW; WINDSHIELD HEAT OFF. IN OUR DSCNT WINDSHIELD HEAT CAME BACK ON. WE WERE IN THE CLOUDS FROM FL260 UNTIL FL040. WE WERE ALSO IN AND OUT OF RAIN. ALL FOUR WINDOWS FOGGED UP INCLUDING THE HEATED PART OF THE WINDSHIELD. IT TOOK THE FO AND MYSELF 15 MINS OF WIPING THE WINDOWS WITH NAPKINS TO GET THE WINDOWS TO A POINT WHERE WE COULD SEE OUT OF THEM. THE NAPKINS WERE SOAKING WET. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FIRST SERIES OF EMBRAER 145 ACFT DELIVERED HAD WINDOW HEAT PANE DELAMINATION PROBS. THE RPTR SAID ANOTHER WINDOW MANUFACTURER BEGAN SUPPLYING WINDOWS BUT THE SAME WINDOW DELAMINATION PROB REMAINED. THE RPTR STATED A NEW PROC WAS INTRODUCED BY THE CARRIER TO CORRECT THE DELAMINATION PROB BY OPERATING THE WINDOW HEAT SYSTEM UP TO FL180 AND TURN OFF THE WINDOW HEAT ABOVE FL180. THIS PROC WORKS FINE ON THE WAY UP; BUT COMING DOWN; THE WINDOWS FOG UP AND SERIOUSLY IMPAIR VISION. THE RPTR STATED THAT IN THIS INCIDENT BOTH CREW MEMBERS WIPED WINDOWS FOR 20 MINS WITH LITTLE OR NO VISION.