DUE TO HIGH FAST AND UNSTABLE APCH; GAR INITIATED BELOW 100 FT. FLT DIRECTORS WERE PURPOSELY TURNED OFF; WHICH SET UP CONFUSION FOR THE SUBSEQUENT GAR. RPTR CAPT THOUGHT THE AUTOTHROTTLES WOULD MAINTAIN SPD RESTR; BUT BECAUSE THE THROTTLES WERE NOT SET APPROPRIATELY; THE AUTOTHRUST WAS NOT ENGAGED. RESULTED IN OVERSPD BELOW 10000 FT.

Narrative

ON APCH INTO LGA RWY 04; I WAS ASKED TO KEEP MY SPD UP AROUND 180 KTS AND TO REMAIN AT A HIGH ALT CLOSE TO THE RWY. ON MY ATTEMPT TO DSND DOWN FROM ALT AND SLOW DOWN MY AIRSPD IN ORDER TO LAND ON RWY 04; THE APCH BECAME UNSTABLE AND THE SINK RATE WARNING WENT OFF DUE TO THE HIGH SINK RATE. AS THERE WAS ANOTHER ACFT IN FRONT OF US AND HAD NOT YET CLRED THE RWY; I WAS FORCED TO DO A GAR. A GAR WITH THE FLT DIRECTORS OFF AND BELOW 100 FT; THE A320 AUTOMATICALLY DISCONNECTS THE AUTOTHRUST SYS. (BAD; BAD; DESIGN.) CONSEQUENTLY; WITH FULL THRUST AND LEVELING OFF AT 3000 FT AND NOT REALIZING THE AUTOTHROTTLES WERE DISENGAGED THE ACFT EXCEEDED 250 KTS BELOW 10000 FT; AS THE THROTTLES WERE AT FULL PWR. AS THE SNOWBALL CONTINUED THE TURN UP THE RIVER FOR ANOTHER APCH WAS LATE DUE TO THE HIGH AIRSPD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: SEVERAL FACTORS SET THE FLC UP FOR THE SPD DEV; NOT THE LEAST BEING A LACK OF ACFT SYS UNDERSTANDING BY THE FLC. RPTR CAPT SAYS THAT IT IS COMPANY PROC TO TURN OFF THE FLT DIRECTORS IF THEY ARE NOT BEING FOLLOWED; WHICH WAS THIS CASE. BECAUSE OF THE HIGH/FAST CONDITION THEY HAD TO DSND AT A RAPID RATE -- MORE THAN BEING INDICATED BY THE FLT DIRECTORS. HOWEVER; TURNING OFF THE FLT DIRECTORS SET THEM UP FOR THE NEXT SURPRISE -- AUTOTHROTTLES DISENGAGED. RPTR MUST HAVE DECIDED AT THE LAST MIN THAT THE APCH WAS TOO UNSTABLE TO CONTINUE BECAUSE THEY WERE BELOW 100 FT WHEN IT WAS COMMENCED. AT THAT TIME TOGA (TKOF GAR) THRUST WAS APPLIED AND THE CLB STARTED WITH HDGS IN CONJUNCTION WITH ATC CLRNC. RPTR DIDN'T KNOW THAT THE AUTOTHRUST WOULD BE REENGAGED IF HE HAD SELECTED CLB THRUST; WHICH SHOULD HAVE BEEN DONE TO COMPLY WITH SOP WHEN 'LVR CLB' WAS FLASHING ON THE FMA (FLT MODE ANNUNCIATOR). THEN; WHEN LEVELING AT 3000 FT WITH MAX THRUST STILL SET; IT DIDN'T TAKE LONG TO EXCEED 250 KTS. THERE WAS CONFUSION IN THE FLC ABOUT WHAT MODE OF OPS THEY WERE IN AND THINKING THAT THE AUTOTHROTTLES WERE ENGAGED; THEY WERE LURED INTO EXPECTING THE THROTTLES TO COME BACK AT THE APPROPRIATE SPD.