JNU CTLR CONCERNED WITH NEW WAKE TURB SEPARATION CRITERION AND ITS APPLICATION.

Narrative

BEECH 1900 DEPARTED FROM FULL LENGTH RWY 8 WITH APPROX 10 KT WIND OUT OF E. 1 MIN 10 SECONDS LATER; I CLRED A PIPER CHEROKEE FOR TKOF FROM AN INTXN -- 2100 FT FROM THE END (RWY 8 AT TXWY B). APPROX 2 MINS 15 SECONDS FROM THE TIME THE BEECH 1900 DEPARTED; I CLRED AN ISLANDER FROM THE SAME INTXN. THE ISLANDER WAS ALSO AN AIR TAXI PAX ACFT. BY THE TIME THE ISLANDER ROLLED; THERE MAY HAVE BEEN 3 MINS BTWN HIM AND THE BEECH 1900; BUT I AM NOT SURE. THERE WAS NOT 3 MINS BTWN THE CHEROKEE AND THE BEECH 1900. 3 MINS IS THE REQUIRED SEPARATION BTWN A SMALL PLUS CATEGORY ACFT DEPARTING FULL LENGTH AND A SMALL ACFT DEPARTING FROM AN INTXN. THERE WAS NO CONCERN FROM ANY OF THE PLTS; AND THERE WAS NO INCIDENT OR WAKE TURB ENCOUNTERED. SEPARATING A SMALL ACFT AND A LARGE ACFT IS EASY AND VERY CLR CUT. HOWEVER; WITH THIS NEW SMALL PLUS CATEGORY; IT IS VERY CONFUSING WHO IS A SMALL PLUS AND WHO ISN'T ONE TYPE OF KING AIR IS A SMALL AND ANOTHER SERIES OF KING AIR IS A SMALL PLUS. IT IS DIFFICULT FOR CTLRS AND PLTS TO KEEP STRAIGHT. IT IS NOT OBVIOUS LOOKING AT THE SIZE OF THE ACFT.