UNCTLED ARPT TFC PATTERN CONFLICT.

Narrative

I WAS ACTING AS SAFETY PLT; WHILE THE PF WAS PRACTICING A LOC 34 APCH AT ARLINGTON. THE AWOS RPTED THE WIND AS 180 AT 7 SO RWY 16 WAS ACTIVE. THE PF HAD ANNOUNCED 'WATON INBOUND FOR LOW APCH RWY 34.' AT ABOUT 3 MI FINAL; ANOTHER AIRPLANE ANNOUNCED 'TURNING R BASE FOR RWY 16.' I THEN ANNOUNCED WE WERE ON 3 MI FINAL AND ASKED THE OTHER ACFT IF THEY WERE FULL STOP. THE REPLY WAS THAT THEY WERE TOUCH AND GO; SO I TOLD THEM THAT WE WOULD SIDESTEP TO THE W. (I HAD THEM IN SIGHT; AND WE WOULD BE ABEAM THE RWY BEFORE THEY COMPLETED THEIR TOUCH AND GO). AT THIS TIME; ANOTHER VOICE ANNOUNCED 'A FLT OF 2 RV-6'S WAS TAKING OFF ON RWY 34!' THIS DIDN'T MAKE ANY SENSE SINCE 16 WAS ACTIVE; BUT I LOOKED FOR THE RV-6'S ON 34; THEY WEREN'T THERE. THEN I LOOKED FOR THEM ON 16; THEY WEREN'T THERE EITHER. WE SIDESTEPPED TO THE W OF 34; AND JUST AS THE PF STARTED TO CLB FOR A MISSED APCH; I SAW THE LEAD RV6 AT 1 O'CLOCK; AND A 750 FT. ALTHOUGH WE WERE 1500 FT TO 2000 FT TO THE W OF THE RVG; I CONSIDERED THIS TOO CLOSE FOR SAFETY ESPECIALLY WHEN I DID NOT HAVE THAT ACFT IN SIGHT SOONER. ANNOUNCING TKOF ON THE WRONG RWY WAS A CONTRIBUTING FACTOR; BUT I SHOULD HAVE ASKED FOR CONFIRMATION; SO WE COULD HAVE SIDESTEPPED FURTHER TO THE W; AND SOONER.