AN A320 FLT CREW LNDG AT ORD EXTENDED THE LNDG GEAR AT 500 FT AGL BECAUSE OF MISCOM BTWN CAPT AND FO.

Narrative

VECTORS TO APCH RWY 9R ORD AT 4000 FT ABOUT 10 MI FROM ARPT AT 210 KTS. TWR TOLD US TO SLOW TO MINIMUM SPD QUICKLY AS WE WERE BEHIND A LNDG B747. I ASKED FOR MANAGED SPEED GEAR DOWN FINAL DSCNT CHK FLAPS FLAPS 2...THEN 3...THEN FULL. WE WANTED TO GET A VISUAL ON THE B747 AS WE DID NOT SEE IT ON TCAS SO WE WERE LOOKING INTENTLY TOWARD THE RWY. I NOTICED THE FO HAD THE CHKLIST IN HIS HAND; BUT SINCE WE WERE TALKING TO ATC AND SEARCHING FOR THE ACFT; I FIGURED THAT WAS THE REASON THAT HE DID NOT BEGIN THE CHKLIST. AT 1000 FT THE FO CALLED 1000 FT. I REPLIED WITH WHAT I SHOULD HAVE PER SOP. AS IS A TECHNIQUE FOR ME; I THEN POINT TO THE GEAR AND FLAP INDICATIONS AND SAY WE HAVE GEAR AND FLAPS -- JUST TO MAKE SURE. AS SOON AS I SAID WE HAVE GEAR; THE FO SAID GEAR DOWN AND PUT THEM DOWN AND BEGAN THE CHKLIST. I WAS TAKEN ABACK AS I THOUGHT THEY HAD BEEN DOWN SINCE 4000 FT. SLIGHTLY FLUMMOXED; I THEN MISTAKENLY WAS THINKING SINCE WE GOT THEM OUT BEFORE 500 FT IT WAS OK TO CONTINUE. ON THE DRIVE HOME; THIS WHOLE EVENT UNNERVED ME AND I THOUGHT ABOUT SEVERAL THINGS. FIRST; I VIOLATED SOP BY NOT HAVING THE GEAR DOWN AND CHKLIST DONE BY THE FAF AND I SHOULD HAVE GONE AROUND. I WAS THINKING AT THE TIME; LNDG CONFIGN BY 500 FT. I BELIEVE THAT I CREATED THE PROB BY CALLING OUT CONFIGN CHANGES TOO QUICKLY AT THE SAME TIME AS WE HAD TO COMMUNICATE WITH TWR AND LOOK FOR TFC ON TOP OF IT BEING LATE. IN THE FUTURE; I AM GOING TO MAKE SURE THAT EACH CONFIGN CHANGE REQUEST IS FOLLOWED BY AN ACTION BEFORE I MOVE ON. IN TALKING WITH THE FO HE HAD NOT HEARD MY REQUEST FOR GEAR DOWN.