AN MD88 ON APCH HAS THE FO'S YOKE SWITCH FAIL IN THE XMIT POS CAUSING TRACON TROUBLES. ON GND HOLDING SHORT MIKE STUCK AGAIN CAUSING TWR PROBS.

Narrative

AFTER ACKNOWLEDGING CLRNC TO CROSS FREAL INTXN AT/ABOVE 5000 FT FOR THE ILS APCH RWY 26R; THE FO'S YOKE SWITCH STUCK IN XMIT. WE DID NOT CATCH THIS PROB; CAUSING THE APCH FREQ TO BECOME JAMMED BY OUR STUCK MIKE. TRACON WAS FORCED TO BREAK OFF THE APCHS OF SOME OTHER ACFT. WITH SIMULTANEOUS APCHS IN PROGRESS; AND WITHOUT COM ABILITY; ATL TRACON HAD TO WAIT UNTIL WE CLRED THE FREQ BY SWITCHING TO TWR BEFORE APCHS COULD RESUME. COM WITH TWR WAS NORMAL; INCLUDING INSTRUCTIONS TO 'HOLD SHORT OF RWY 26L AT THE W END.' IT WASN'T UNTIL WE HELD THERE FOR A BIT AND I NOTICED I WASN'T HEARING ANY MORE COM FROM TWR; SUCH AS ACFT BEING CLRED FOR TKOF; ETC; THAT WE DISCOVERED THE STUCK MIKE. THE FO HAD NOTED ENRTE THAT HIS YOKE SWITCH WOULD STICK IN XMIT. KNOWING THIS; WE SHOULD HAVE BEEN MORE ALERT TO THE POTENTIAL OF CAUSING A STUCK MIKE PROB. I SHOULD HAVE INSTRUCTED THE FO TO USE HIS HAND MIKE. I USE MINE ROUTINELY ENRTE. BUT IN TODAY'S WORLD OF HEADSETS/BOOM MIKES; MOST PLTS NEVER USE THE HAND MIKE. ALSO; ALL I CAN FIGURE IS THAT WE GOT BUSY LOOKING FOR THE ARPT IN THE HAZE; LOOKING FOR THE ACFT WE WERE FOLLOWING; RUNNING LNDG CHKLIST; ETC; SUCH THAT WE SIMPLY FAILED TO NOTICE OUR STUCK MIKE. BUT THIS IS NO EXCUSE. WE SHOULD HAVE NOTICED THE APCH FREQ WAS UNUSUALLY QUIET. IN FACT; IT WAS THIS UNUSUAL QUIETNESS I NOTICED WHILE HOLDING SHORT OF RWY 26L AFTER LNDG AND AWAITING XING CLRNC THAT MADE ME QUERY THE FO ABOUT THE POSSIBILITY OF HIS YOKE SWITCH BEING STUCK. (BY THE WAY; EVEN AFTER DISCOVERING WE'D BEEN COM JAMMING ATC; THE FO STILL WANTED TO USE HIS YOKE SWITCH/BOOM MIKE. I HAD TO DIRECT HIM TO STOP AND USE HIS HAND MIKE FOR TAXI INTO THE GATE.