ALTDEV ALT EXCURSION.

Narrative

FO FLYING; CAPT ON RADIO; SEA-JNU LEG. GIVEN CLRNC TO JNU ARPT VIA SSR VOR; SSR 360 DEG RADIAL LYNNS INTXN; EXPECT CLRNC FOR LDA-2 RWY 8 JNU; EXPECT NO DELAY FROM ZAN. CLRED FROM FL350 TO 11000. PASSING APPROX FL200; RECEIVED CLRNC TO 9000 AND 'RPT SSR VOR; EXPECT NO DELAY.' HEARD AN ACR FLT WAS CLBING TO 8000; ON BARLO 6 DEP (IMC CONDITIONS FROM 19000 TO 4500). APCHING SSR VOR; ASKED ZAN IF A TURN IN HOLDING AT SSR WOULD HELP. ZAN JUST SAID TO 'CONTINUE.' WE CROSSED SSR VOR AT APPROX 10500; AND RPTED XING TO ZAN. 5 MI N OF SSR VOR OBSERVED LGT PASS IN OPPOSITE DIRECTION ENRTE SSR ON OUR TCASII. WE WERE CONCERNED WITH BEING 'HIGH' ON OUR DSCNT PROFILE AND CONTINUED DSCNT TO 5100. HEARD A VERY WEAK; BADLY BROKEN AND UNINTELLIGIBLE XMISSION FROM ZAN APCHING LYNNS INTXN. BROADCAST IN THE BLIND TO ZAN THAT WE WERE SWITCHING TO JNU TWR. JNU TWR ROGERED OUR POS AT LYNNS INTXN; AND TOLD US TO RPT BARLO INTXN. WE CONTINUED WITH THE JNU LDA-2 RWY 8 APCH WITH REMAINDER OF FLT UNEVENTFUL. SUPPLEMENTAL INFO FROM ACN 224239: DSCNT WAS NEVER STOPPED AND AT APPROX 8200 FT RECEIVED A TCASII RA WITH COMMANDED 2000 FPM DSCNT. FOLLOWED DSCNT COMMAND AND RA PASSED NO CLOSER THAN 1 1/2 MI OFF R SIDE. SWITCHED TO JNU TWR AFTER RA AND ASKED IF WE WERE NOW CLRED FOR APCH. SUPPLEMENTAL INFO FROM ACN 224237: BEING CONCERNED WITH BEING HIGH ON OUR APCH PROFILE AND BEING ON SSR 360 DEG RADIAL; CAPT PUT 5100 FT INADVERTENTLY IN ALT SELECT. CONTINUED DSCNT TOWARD 5100 FT.