A PA31 CARGO PLT INADVERTENTLY LANDED ON A CLOSED RWY AT ZZZ.

Narrative

AFTER CHKING WX AND NOTAMS USING AN INTERNET BRIEFING PROVIDER FOR THE PROPOSED 30 MIN FLT FROM FLG TO ZZZ; THE CAPT DEPARTED FLG. OVERFLYING ZZZ; IT WAS NOTED THAT THERE WERE SEVERAL VEHICLES AROUND THE OVERRUN/BLAST PAD AREA OF RWY 15/33; BUT NO 'X' ON THE RWY; OR REPLY TO RADIO XMISSIONS OF LNDG INTENTIONS. UPON FINAL APCH; THE CAPT NOTED THE RWY ITSELF WAS CLR OF PERSONS AND VEHICLES AND ELECTED TO LAND. APPROX 5 MINS AFTER LNDG; ONE OF THE VEHICLES APCHED THE ACFT AND THE DRIVER STATED THAT THEY WOULD SOON BE WORKING ON THE RWY. HE ALSO INFORMED THE PLT THAT THE ARPT WAS CLOSED TO ALL BUT AMBULANCE FLTS DURING DAYLIGHT HRS DURING FEB/TUE-WED/04. THE PLT; UNAWARE OF THIS NOTAM AND A DAILY USER OF THE ZZZ ARPT; AGREED TO DEPART IMMEDIATELY. A FURTHER INVESTIGATION OF NOTAMS ISSUED BY THE PRESCOTT FSS DID REVEAL THE ONE IN QUESTION OVER THE INTERNET BRIEFING PROVIDER AT FLG. CONTRIBUTING FACTORS WERE COMPLACENCY; A RUSHED PREFLT NOTAM CHK; AND OVER-RELIANCE ON THE INTERNET BRIEFING PROVIDER SYS IN PLACE OF AN FSS BRIEFING. CORRECTIVE ACTION WILL INCLUDE A CALL TO FSS FOR NOTAMS AND A MORE THOROUGH PREFLT WX AND NOTAM REVIEW. ADDITIONALLY; IT WOULD HAVE BEEN HELPFUL TO MARK THE RWY APPROPRIATELY FOR ITS CLOSURE AND/OR TO SUPPLY THE GND PERSONNEL WITH A TRANSCEIVER. THE ARPT MGR COULD HAVE HELPED BY INFORMING US OF THE IMPENDING CLOSURE.