AN A320 GND HOLDING ON THE RWY AT PHX EXPERIENCES A STUCK MIKE. A B737 ON FINAL HAS TO BE SENT AROUND.

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I WAS THE COPLT ON FLT FROM PHX TO TUS. WE WERE APCHING THE HOLD SHORT LINE FOR RWY 26L IN PHOENIX; AZ. TWR TOLD US TO POS AND HOLD ON RWY 26L AND SAID THERE WAS A B737 ON A 5 MI FINAL. I READ BACK THE POS AND HOLD CLRNC AND WE TAXIED INTO POS ON RWY 26L AND WAITED FOR AN ACFT TO CLR THE RWY. AFTER ABOUT 1 MIN WE GOT AN ECAM WARNING ON OUR EFIS SYS TELLING US THAT WE HAD A STUCK MIKE. BOTH THE CAPT AND I SWITCHED THE XMITTER SELECTOR TO A DIFFERENT RADIO AND NOW HEARD THE CTLR TELLING THE B737 TO GAR. WE THEN FOUND THE HAND MIKE ON THE COPLT SIDE WAS SHORTING OUT AND STICKING. I CALLED TWR USING MY PUSH TO TALK SWITCH AND WE WERE CLRED FOR TKOF. AFTER LNDG IN TUS; THE TWR ASKED US TO CALL PHOENIX TWR. THE CAPT CALLED AND EXPLAINED THE PROB WAS CAUSED BY A FAULTY MIKE. THE AIRBUS 320 HAS 2 HAND MIKES; 2 PUSH TO TALK SWITCHES ON THE RADIO CTL PANEL; 2 PUSH TO TALK SWITCHES ON THE RESPECTIVE CTL STICKS. THE ONLY WAY TO SEE IF A XMISSION IS TAKING PLACE IS AFTER 1 MIN OF CONTINUOUS XMISSION YOU GET AN ECAM WARNING ON EFIS.