FAI CTLR EXPRESSED CONCERN REGARDING LOCAL MGMNT'S CHANGE TO NATIONAL WEIGHT CAT FOR ONE LCL COMPANY DASH-8 ACFT.

Narrative

ON APR/XA/07 I WAS BRIEFED VIA WRITTEN MEMORANDUM THAT HENCEFORTH ALL DASH-8 ACFT OPERATED BY FBO 'SHALL BE HANDLED AS SMALL-PLUS (S+) WT-CLASS FOR SEPARATION PURPOSES.' THIS MEMORANDUM IS CONTRARY TO THE WT CLASSIFICATION FOR THIS ACFT TYPE THAT IS PUBLISHED IN FAAO 7110.65. THIS MEMORANDUM IS SIGNED BY THE ACTING FACILITY MGR; BUT I BELIEVE IT WAS ORIGINALLY AUTHORED BY THE ANCHORAGE HUB MGR. THIS MEMORANDUM IS VERY PUZZLING FOR THE FOLLOWING REASON: 1) IT IS NOT A NATL CHANGE; ONLY FACILITIES IN THE ANCHORAGE HUB ARE PARTICIPATING; EVEN THOUGH THIS CHANGE IS TO A NATL DIRECTIVE; AND DASH-8 ACFT ARE OPERATED WORLDWIDE. 2) ONLY DASH-8 ACFT OPERATED BY FBO ARE INCLUDED IN THIS CHANGE. 3) THE FLEET AT FBO IS NOT STATIC; EVEN IF DATA WERE 100% TRUE TODAY; THE FLEET COULD ENCOMPASS LARGER; HEAVIER DASH-8 ACFT TOMORROW; AND ANC HUB ATC FACILITIES WOULD HAVE NO BASIS FOR PROVIDING MORE THAN S+ SEPARATION FOR ACFT FOLLOWING THEM. THIS SITUATION NEEDS TO BE INVESTIGATED. AD HOC CHANGES TO THE WAKE TURB SEPARATION STANDARDS ARE NOT A GOOD IDEA.