B737-300 CREW TOOK OFF WITH THE AFT CARGO DOOR OPEN.

Narrative

ON TAXI OUT FOR DEP ON RWY 36R; WE RECEIVED A CALL FROM TPA OPS THAT SOMEONE ON THE GND THOUGHT A CARGO DOOR WAS OPEN ON A TAXIING ACFT. IT WAS STILL DARK; AND WE WERE THE LAST OF 3 COMPANY ACFT ON THE TXWY. WE CHKED OUR OVERHEAD LIGHTS; AND ALL WERE EXTINGUISHED. WE PUSHED THE ANNUNCIATOR RECALL AND CHKED EACH DOOR LIGHT TO ENSURE THAT THEY WORKED. ALL INDICATIONS WERE NORMAL. BY THIS TIME; ONLY OTHER COMPANY ACFT WAS STILL ON THE GND. OPS WAS TRYING TO REACH THAT ACFT AND WE TRIED TO ASSIST; BUT HE STARTED HIS TKOF ROLL BEFORE WE COULD MAKE CONTACT. WE WERE CLRED FOR TKOF; AND WE DEPARTED FROM TPA. ON CLBOUT; THE ACFT WOULD NOT PRESSURIZE. WE GOT AN AUTO FAIL LIGHT; AND THE STANDBY LIGHT ILLUMINATED. THE OUTFLOW VALVE WAS CLOSED; BUT THE CABIN WAS STILL CLBING AT 2000 FPM. WE LEVELED OFF AT 5000 FT; AND TOLD DEP THAT WE NEEDED TO RETURN TO THE ARPT. AT 210 KTS; WE COULD FEEL SOME VIBRATION IN THE ACFT; AND CONFIRMED THIS WITH THE CABIN CREW. I ADVISED THE PAX OF THE PRESSURIZATION PROB; AND WE RETURNED TO TAMPA ARPT WITH AN UNEVENTFUL LNDG. ONCE WE REACHED THE GATE; OUR AFT CARGO DOOR WAS FOUND TO BE IN THE FULL OPEN POS. THE CARGO BIN HAD BEEN LOADED WITH FREIGHT; AND IT WAS ALL ACCOUNTED FOR. TAMPA MAINT CHKED THE AFT CARGO DOOR AND FOUND NO DAMAGE. OUR COCKPIT DOOR WARNING LIGHT SYS WAS CHKED; AND THE AFT CARGO DOOR LIGHT WAS STILL EXTINGUISHED (LAMP CHKED OK). THE LIGHT SYS WAS DEFERRED UNDER MEL 52-3; AND WE CONTINUED ON TO OUR DEST. THE CAUSE OF THE EVENT WAS THE FAILURE OF THE GND CREW TO SECURE THE DOOR; AND FAILURE TO VERIFY THAT AS REQUIRED BY PUSHBACK PROCS. THE REMEDY WOULD BE LIMITED TO GND OPS DEPT. SUPPLEMENTAL INFO FROM ACN 562825: WE CHKED THE OVERHEAD DOOR LIGHTS AS WELL AS THE MASTER CAUTION RECALL WITH NO INDICATION OF AN OPEN DOOR. UPON DEP FROM TPA; THE ACFT DID NOT PRESSURIZE. UPON ARR AT THE GATE; IT WAS DISCOVERED THAT THE ACFT CARGO DOOR WAS OPEN. A COMPANY MECH CAME TO THE COCKPIT AND CONFIRMED THAT THERE WAS NO ASSOCIATED LIGHT ON FOR THE AFT CARGO DOOR. ADDITIONALLY; THE MASTER RECALL FAILED TO PRODUCE A 'DOORS' LIGHT.