Narrative:

I unknowingly operated from ord/msn/atw in violation of the MEL after the sun set. This aircraft had the wind screen heat placarded as inoperative, however, the maintenance log indicated the wind screen heat was in high heat at all times. The MEL indicates if one is inoperative, it should be operated day VMC only. The dispatch release indicated IFR operation with restrictions. It did not indicate IFR VMC daylight only. This aircraft had been operating on company routes about 36 hours before I received it at ord. No other pilot or dispatcher had noticed this applicable restriction. The window heat problem was entered into the maintenance log about 36 hours before I received the aircraft. I did not think, at the time I received the aircraft, that the window heat operating in the high heat mode would make this window heat be classified as inoperative. The landing at atw was after dark at approximately XX35 CDT. I was informed about the problem 2 days later. The moral of the story--mels may have surprises. The WX was clear at all times--cavu.

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Original NASA ASRS Text

Title: ACR MLG VIOLATED MINIMUM EQUIPMENT LIST REQUIREMENT BY FLYING AT NIGHT WITH THE COCKPIT WINDOW HEAT INOPERATIVE.

Narrative: I UNKNOWINGLY OPERATED FROM ORD/MSN/ATW IN VIOLATION OF THE MEL AFTER THE SUN SET. THIS ACFT HAD THE WIND SCREEN HEAT PLACARDED AS INOP, HOWEVER, THE MAINT LOG INDICATED THE WIND SCREEN HEAT WAS IN HIGH HEAT AT ALL TIMES. THE MEL INDICATES IF ONE IS INOP, IT SHOULD BE OPERATED DAY VMC ONLY. THE DISPATCH RELEASE INDICATED IFR OPERATION WITH RESTRICTIONS. IT DID NOT INDICATE IFR VMC DAYLIGHT ONLY. THIS ACFT HAD BEEN OPERATING ON COMPANY ROUTES ABOUT 36 HRS BEFORE I RECEIVED IT AT ORD. NO OTHER PLT OR DISPATCHER HAD NOTICED THIS APPLICABLE RESTRICTION. THE WINDOW HEAT PROB WAS ENTERED INTO THE MAINT LOG ABOUT 36 HRS BEFORE I RECEIVED THE ACFT. I DID NOT THINK, AT THE TIME I RECEIVED THE ACFT, THAT THE WINDOW HEAT OPERATING IN THE HIGH HEAT MODE WOULD MAKE THIS WINDOW HEAT BE CLASSIFIED AS INOP. THE LNDG AT ATW WAS AFTER DARK AT APPROX XX35 CDT. I WAS INFORMED ABOUT THE PROB 2 DAYS LATER. THE MORAL OF THE STORY--MELS MAY HAVE SURPRISES. THE WX WAS CLEAR AT ALL TIMES--CAVU.

Data retrieved from NASA's ASRS site as of August 2007 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.