A B747-400 FO EXECUTES A GAR IN A WINDSHEAR AT 200 FT. WITH THE AUTOTHROTTLES ENGAGED THE ACFT ACHIEVED 280 KTS WHILE LEVELING AT 4000 FT.

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NORMAL RADAR VECTORING TO A 15 MI FINAL FOR ILS/VISUAL RWY XX. DURING THE VECTORING IN AND OUT OF CLOUDS WITH CONTINUOUS LIGHT TO MODERATE TURB. SURFACE WINDS WERE 260 DEGS AT 25 KTS GUSTING TO 45 KTS RPTED. AT INTXN; XFER TO TWR AND CLRED TO LAND WITH WINDSHEAR ADVISORY AND CURRENT WIND SIMILAR TO THE ABOVE. FO WAS HAND FLYING WITH AUTOTHROTTLES ENGAGED. TURB REMAINED THE SAME DOWN TO ABOUT 100-200 FT. AIRSPD WAS WITHIN LIMITS AROUND THE TARGET SPD OF 162 KTS. AT ABOUT 200 FT A MASSIVE WIND INCREASE HIT US AND THE AIRSPD JUMPED OVER TARGET BY ABOUT 30-35 KTS. I SAID GO AROUND AND THE FO IMMEDIATELY INITIATED THE GAR. AS PWR REACHED TOGA; THE BACK SIDE OF THE AIRSPD INCREASE HIT US AND AIRSPD DROPPED BELOW TARGET. BECAUSE OF OUR LIGHT WT (538.0) WE FLEW RIGHT THROUGH THE DECREASE AND BEGAN CLBING. THE TWR GAVE US A L TURN TO XWIND AND DURING THE CLB; CLEAN-UP BEGAN. THE SPD WINDOW ON THE MCP WAS OPENED TO 250 KTS; BUT SOMEWHERE IN THE MISSED APCH CONFUSION A VERT SPD MODE WAS NOT SELECTED AND THE ENGS REMAINED IN THRUST REF. THE FLAPS WERE RETRACTED ON SCHEDULE BUT THEN APCHING THE ASSIGNED ALT OF 4000 FT THE AIRSPD EXCEEDED 250 KTS. A COUPLE OF FRANTIC MOMENTS OF 'WHAT IS IT DOING NOW?' AND A VERT MODE WAS SELECTED AND THE SPD ARRESTED AND BROUGHT BACK TO 250 KTS AND THEN EVENTUALLY TO THE APCH CTL ASSIGNED SPD OF 210 KTS. THE SECOND APCH IN THE SIMILAR CONDITIONS RESULTED IN A NORMAL LNDG. THE OVERSPD COULD HAVE BEEN AVOIDED IF THE FMA'S WERE MORE CLOSELY MONITORED AND IF THE PF WOULD HAVE DISCONNECTED AUTOMATION (AUTOTHROTTLES) WHEN AUTOMATION WASN'T GIVING WHAT WAS NECESSARY! SUPPLEMENTAL INFO FROM ACN 809626: ONCE ON DOWNWIND AND CLEAN AT 4000 FT; THE ACFT ACCELERATED; I'M NOT SURE OF THE THRUST MODE. I CALLED 'YOU'VE GOT TO SLOW DOWN.' THE FO WAS HAND FLYING WITH AUTOTHRUST ENGAGED AND TRIED TO PULL THRUST BACK BUT THROTTLES KEPT ADVANCING. MAX INDICATED AIRSPD 283 KIAS. THE CTLR ISSUED CLB 5000 FT; I THINK TO GIVE US A CHANCE TO BLEED ENERGY. WITH THE SPD UNDER CTL; A NORMAL SECOND APCH AND LNDG WAS ACCOMPLISHED. WITH A GOOD TAILWIND WE HAD ABOUT 330 KT GND SPD ON DOWNWIND! FACTORS WERE: PERFORMING A MANEUVER WE DON'T GET TO DO MUCH. FO'S FOCUS ON ALT CTL/CONFIGN CHANGES WHILE NOT AWARE OF THRUST MODE.