C172 PLT TAKES OFF AND FLIES FOR OVER 1 HR WITH TOW BAR ATTACHED TO NOSE GEAR.

Narrative

I ARRIVED AT THE HANGAR ABOUT XA40 AND PROCEEDED WITH THE PREFLT IN THE HANGAR. AFTER COMPLETING THE CHKLIST PREFLT; MY PAX ARRIVED FOR THE FLT AT XB00. I PROCEEDED TO PULL THE C172 OUT OF THE S FACING T-HANGAR; STOPPING IT IN FRONT OF THE ADJACENT HANGAR FACING E. I INSTRUCTED THE OBSERVER TO PARK HIS VEHICLE IN THE HANGAR WITH MY VEHICLE SO AS NOT TO BLOCK ANYONE'S ACCESS IN OUR ABSENCE. WE DISCUSSED THE OBJECTIVES OF THE FLT JUST INSIDE THE HANGAR. WE THEN PROCEEDED TO THE ACFT CABIN DOORS FROM THE REAR; WHERE I CONDUCTED THE CREW BRIEFING FOR EMER PROCS. DUE TO THE 80+ DEG HEAT; I LEFT THE PLT'S WINDOW OPEN AND INSTRUCTED THE OBSERVER TO LEAVE HIS DOOR AJAR DURING TAXI TO INCREASE CABIN VENTILATION. MY FIRST INDICATION THAT SOMETHING WAS AMISS WAS WHEN I HEARD A SLIGHT METALLIC RATTLING OVER THE ENG AND AIR INDUCED INTERCOM NOISE AS WE WERE TAXIING. WHEN I TOUCHED THE WINDOW LATCH OF THE OPEN WINDOW; THE NOISE CEASED. I PROCEEDED TO TAXI FROM THE NW T'S VIA TXWYS J; B; AND C TO RWY 1 WHERE I WAS CLRED FOR TKOF. AFTER AN UNEVENTFUL 1.5 HR FLT; I WAS CLRED TO LAND LONG ON RWY 1. AS I CROSSED THE THRESHOLD AT ABOUT 150 FT; A PLT AWAITING DEP NOTICED THE TOW BAR ATTACHED TO THE NOSE GEAR AND RPTED IT TO THE TWR. THE TWR INSTRUCTED ME TO GO AROUND AND I COMPLIED. AS THE FOLLOWING AIR TFC CLRED THE RWY; I WAS AGAIN CLRED TO LAND ON RWY 1; THIS TIME WITH TWR RESPONDED CRASH TRUCKS STANDING BY. I DID NOT DECLARE AN EMER. AFTER LNDG I REQUESTED AND WAS APPROVED TO SHUT DOWN ON THE RWY. I REMOVED THE TOW BAR AND DID A QUICK INSPECTION. I THEN RESTARTED THE ACFT AND RETURNED TO THE HANGAR. A FOLLOW-UP INSPECTION REVEALED NO EVIDENCE OF PROP CONTACT OF ACFT CONTACT WITH THE TOW BAR. IN REFLECTION; I DID NOT DO MY CUSTOMARY 'BIG PICTURE WALKAROUND' JUST PRIOR TO BOARDING THE ACFT. I ALSO TOO QUICKLY DISMISSED THE METALLIC NOISE AS A VIBRATING OPEN WINDOW LATCH. SOME VALUABLE LESSONS WERE REINFORCED TO THIS 1300-HR PLT; FORTUNATELY WITHOUT CAUSING DAMAGE OR INJURY.