A GND CREW COMPLETED A CL65 PUSH BACK; DISCONNECTED THE TUG FROM THE TOW BAR BUT NOT THE ACFT. THE FLT CREW WAS NOT NOTIFIED TO SET BRAKES. THE ACFT NOSE CONE CONTACTED THE TUG AS IT ROLLED FREELY.

Narrative

THE CREW HAD BEEN SITTING AT THE ARPT FOR 12 HRS WAITING FOR ZZZ WX TO GET BETTER SO A GND STOP WOULD BE LIFTED AND WE COULD OPERATE OUR FLT. THE PUSHBACK WAS NORMAL; THE SECOND ENG WAS STARTING. I HEARD A METALLIC NOISE AND LOOKED OUT THE WINDSHIELD. IT LOOKED LIKE THE TUG AND ACFT WERE MOVING CLOSER TOGETHER. I SAID STOP; STOP; AND BY THAT TIME WE RAN INTO THE TUG; THE NOSE CONE PUSHING OUT THE TUG WINDSHIELD. GND CTL; DISPATCH; MAINT; FLT ATTENDANT; AND PAX WERE ALL NOTIFIED AND KEPT UP TO DATE WITH WHAT HAD HAPPENED. THE TOW BAR HAD LODGED ITSELF UNDER THE TUG WHILE STILL BEING ATTACHED TO THE NOSEWHEEL. THE GEAR PINS WERE INSTALLED; THE 5 PAX WERE DEPLANED AND ESCORTED BACK TO THE TERMINAL. CONTRACT MAINT ARRIVED. THE TOW BAR WAS DISCONNECTED; NOSE CONE INSPECTED AND NO OTHER DAMAGE WAS EVIDENT. WE WERE TOWED BACK TO THE GATE. NORMALLY; THE PUSH CREW WILL CALL 'PUSHBACK COMPLETE; SET BRAKES;' THE CAPT WOULD REPLY 'BRAKES ON.' THEN THEY WILL INDICATE THE TOW BAR DISCONNECT AND TORQUE LINKS CONNECTED. NOTHING WAS SAID. AS THE PUSH ENDED; THE GND PERSONNEL DISCONNECTED THE TOW BAR WITHOUT THE COMMAND TO. THE TUG DRIVER INDICATED THAT THE OTHER GND CREW HAD PULLED THE TOW BAR PIN PREMATURELY. THE FOLLOWING DAY OUR CREW OPERATED A FLT WITH THAT AIRPLANE WITH A NEW NOSE CONE. COMPLACENCY HAD A PART IN THIS AS PUSHBACK IS A ROUTINE; STRESSLESS EVENT. HOWEVER; AS THIS INCIDENT SHOWS; THIS IS NO TIME TO RELAX ONE'S AWARENESS WHEN YOU DEPEND ON OTHERS TO DO THEIR JOB CORRECTLY.