A B737-300 FLC HAS A LOSS OF COM FREQ ON SHORT FINAL DURING A CAT IIIA HUD ILS APCH TO RWY 24L AT LAX; CA.

Narrative

ON APCH TO LAX WHEN THE WX WAS 2200 FT RVR; WE BRIEFED A CAT IIIA APCH. WHEN SLOWED ON APCH; WE SELECTED FLAPS 5 DEGS AND INITIALLY HAD A LEADING EDGE FLAPS TRANSIT LIGHT THAT LATER CLRED ITSELF. ON APPROX 12 MI FINAL; WE WERE GIVEN A 360 DEG TURN AND FINALLY CLRED LOWER ONCE WE WERE OUTBOUND IN THIS TURN BECAUSE OF A SPACING PROB THAT WAS DEVELOPING WITH A LIFEGUARD FLT THAT THEY WERE SQUEEZING IN AHEAD OF US. ONCE CLRED FOR THE APCH; A NORMAL CAT IIIA HUD COMPANY PROCS APCH WAS FLOWN WITH THE WX NOW RPTED AS INDEFINITE. CEILING 200 FT; OVCST 6000 FT; RVR. UPON CLRING THE RWY WE REALIZED THAT THE #1 COM HAD INADVERTENTLY BEEN FLIPPED OFF TWR FREQ BACK TO SOCAL APCH FREQ AND THAT WE MAY HAVE BEEN OFF TWR FREQ FOR A SHORT PERIOD OF TIME ON FINAL. IMMEDIATELY ON ARR AT THE GATE; I CONTACTED THE CURRENT LAX TWR SUPVR. HE VOICED NO CONCERN IN REF TO THIS SIT BUT WANTED TO ENSURE WE KNEW THAT WE WERE TO STAY ON THE TWR FREQ BTWN THE RWY 24L&R RWYS. HE ALSO SAID HE HAD NO REASON OR INTENT TO PURSUE ANY ACTION SINCE NOTHING HAD REALLY OCCURRED (NO INFRINGEMENT). I THINK THAT THE FOLLOWING FACTORS CONTRIBUTED TO THIS SIT: 1) WORKLOAD DEALING WITH A LEADING EDGE TRANSIT LIGHT. 2) ADDED WORKLOAD OF THE HGS APCH. 3) ADDED WORKLOAD OF THE 360 DEG TURN ON 12 MI; 10 MI FINAL IN IMC. 4) BEING KEPT HIGH ON APCH DUE TO A LIFEGUARD FLT SLOWING MORE THAN SOCAL APCH HAD ANTICIPATED. 5) THE DESIRE TO CONSERVE FUEL FOR THE POSSIBILITY OF A DIVERT (A DIVERT THAT MAY HAVE INCLUDED PERFORMANCE CONSIDERATIONS OF A LEADING EDGE DEVICE PROB). 6) LOCATION OF THE BRIGHT/DIM BUTTON ON THE HGS CTL PANEL; RIGHT ABOVE THE COM 1 XFER TOGGLE FOR SWAPPING FREQS (FO REMEMBERS BRIGHTENING THE HGS CTL HEAD DISPLAY TO VERIFY A CAT IIIA MODE).