A-320 FORCED TO GAR DUE TO THERMAL ACTIVITY AND RESULTING TURB; EXCEEDS GAR ALT.

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DURING NORMAL VFR APCH TO PHX-26R WE EXPERIENCED A FAIR AMOUNT OF THERMAL ACTIVITY (OUTSIDE TEMP APPROX 100 DEGS F). CAUSING PLUS OR MINUS ALTDEVS FROM GS. NORMAL FOR THIS TYPE OF DAY. ACFT (A-320) WAS BEING HAND FLOWN WITH AUTOTHROTTLES ON. NO FLT DIRECTORS OR AUTOPLTS ON. BELOW 200 FT AGL ACFT WAS ON GS; FLARE AND RETRAD OF PWR NORMAL. JUST PRIOR TO TOUCHDOWN WIND GUST AND/OR THERMAL ACTIVITY CAUSED ACFT TO CLB FROM 10 FT RADIO ALT TO 30 FT RADIO ALT. AIRSPD INCREASED ABOUT 5 KTS OVER V APCH. IF LNDG HAD BEEN 'FORCED' TOUCHDOWN WOULD HAVE BEEN BEYOND MIDFIELD SO GAR WAS INITIATED. SINCE THROTTLES HAD BEEN RETARDED TO IDLE CONSIDERABLE TIME WAS REQUIRED FOR ENGS TO REACH GAR THRUST. AFTER PASSING 2500 FT MSL WE WERE SWITCHED BACK TO APCH FROM TWR. CAPT WAS OPERATING RADIOS AND SETTING ALT ASSIGNED OF 4000 FT AND CONFIRMING HDG. BY THE TIME 4000 FT WAS ASSIGNED AND CONFIRMED BY CAPT WE WERE RAPIDLY CLBING THROUGH 3200-3500 FT AND EXPERIENCING THE SAME UPS AND DOWNS DUE TO THERMAL ACTIVITY. IN ATTEMPTING TO SMOOTHLY LEVEL OFF IN THE BUMPY AIR WHILE STILL COMPLETING THE ACFT CLEAN UP AND TURNING THE AUTOTHROTTLES BACK ON; ETC; I EXCEEDED MY ALT OF 4000 FT. WE WERE ESSENTIALLY LEVEL BY 4150-4200 FT AND THEN ONCE AGAIN 'BALLOONED' TO APPROX 4300 FT DUE TO THERMAL TURB. POSSIBLE CAUSAL FACTORS: FAILURE ON MY PART TO BE MENTALLY PREPARED FOR GAR AND THUS BE MORE EFFICIENT IN GETTING THE SYS BACK ON LINE TO AND IN GAR PROFILE. BEING #1 TO ARPT IN VFR CONDITIONS WITH NO TFC AT HOLD SHORT NO REASON TO CONSIDER A GAR. CAPT WAS ON ONLY HIS SECOND TRIP SINCE TRAINING ON ACFT (LESS THAN 100 HRS) AND RATHER THAN TRYING TO RESPOND TO QUESTIONS ABOUT WHY AUTOTHROTTLES; ETC; WEREN'T ON DURING GAR; ETC. I SHOULD HAVE ASKED HIM TO WAIT UNTIL ACFT WAS ON DOWNWIND. CORRECTIVE ACTIONS: ALWAYS BE MENTALLY PREPARED FOR GAR NO MATTER HOW GOOD THE WX. WHEN FLYING WITH 'NEW TO THE EQUIP' PLTS OR ANYONE WITHOUT RECENT EXPERIENCE; REVIEW WHAT WILL/WILL NOT WORK ON GAR. THIS GAR WAS VERY UNUSUAL IN THAT THROTTLES WERE ALREADY TO IDLE AND THEREFORE AUTOTHROTTLES DISCONNECTED. ALSO FO'S WERE OFF -- (FLT DIRECTOR'S) SO THERE WASN'T THE USUAL VERT GUIDANCE TO HELP WITH GAR.