DURING AN ILS APCH TO RWY 13 WITH A 400 FT CEILING; AN LJ35 FLT CREW LANDS WITHOUT LNDG CLRNC AT MFE; TX.

Narrative

VALLEY APCH HAD VECTORED US TO THE LOC FOR THE ILS RWY 13 APCH INTO MILLER INTL ARPT. THE ATIS WAS RPTING 400 FT OVCST; VISIBILITY 5 MI. THE APCH PROCEEDED NORMALLY. THE APCH CHKS AND BEFORE LNDG CHKS HAD BEEN ACCOMPLISHED AND UPON PASSING THE MARKER; A DSCNT WAS INITIATED. DURING THIS LEG; THE CAPT WAS FLYING THE ACFT. AS I RECALL; VALLEY APCH HANDED US OFF TO MCALLEN TWR WELL INSIDE OF THE MARKER. AS WE WERE RECEIVING THE HDOF; A PAX LEANED FORWARD IN TO THE CABIN AND BEGAN 'TAPPING' ME ON THE SHOULDER. I MOVED ONE SIDE OF MY HEADSET AWAY FROM MY EAR TO FIND OUT IF A PROB EXISTED AND REMINDED THE PAX TO REMAIN SEATED AS WE WERE ABOUT TO LAND. (PRIOR TO THE INTERRUPTION AND APCH PHASE; THE SEAT BELT SIGN WAS ON AND CABIN AND PAX VERIFIED CLR AND READY FOR LNDG.) DURING THE PAX INTERRUPTION; THE CAPT'S ATTN WAS ALSO MOMENTARILY DIVERTED AND HE MOTIONED FOR THE PAX TO REMAIN SEATED. THE PAX DISTR OCCURRED APPROX 500-600 FT ABOVE MINIMUMS. AFTER DEALING WITH THE PAX; OUR ATTN RE-FOCUSED ON THE APCH. IN A MATTER OF SECONDS; THE RWY BECAME VISIBLE; A FINAL CHK WAS COMPLETED; THE RWY WAS CONFIRMED CLR AND WE LANDED. AFTER CLRING THE RWY; WE WERE UNABLE TO RECEIVE MCALLEN TWR ON FREQ; SO WE SWITCHED TO GND. GND ADVISED US; WE HAD LANDED WITHOUT A CLRNC; SO THE CAPT CALLED THE TWR AFTER UNLOADING THE PAX. THE CAPT EXPLAINED A PAX INTERRUPTION HAD TAKEN PLACE DURING THE MOMENTS WE WERE SWITCHING FREQS. THE TWR EXPLAINED HE WAS TRYING TO CONTACT US WITHOUT ANY REPLY. THE CAPT APOLOGIZED FOR US AND SAID WE WOULD NOT LET HAPPEN AGAIN. BEYOND THE PAX INTERRUPTION; WE COULD NOT EXPLAIN HOW THE HDOF WAS MISSED. ANOTHER OF OUR COMPANY ACFT HAD LANDED AHEAD OF US AND EXPLAINED THEY HAD HEARD THE TWR TRYING TO CONTACT US WITHOUT A REPLY. THEY ALSO MENTIONED THEY HAD TURNED UP THE VOLUME TO BETTER HEAR THE CTL TWR. THE CAPT AND I RETURNED TO THE ACFT; DISCUSSED THE EVENT AND TRIED CONTACTING THE TWR AND GND ON OUR #1 COM. BOTH FREQS WORKED FINE AND WITHOUT PROBS THE REMAINDER OF THE DAY. AT NO POINT DURING THE APCH DID THE ACFT DEVIATE FROM THE LOC OR GS AS OUR PRIMARY ATTN WAS ON ACFT CTL. HOWEVER; FOR A MOMENT; BOTH MY THOUGHT PROCESS AND ROUTINE; AS WELL AS THE CAPT'S; WERE DISTR ENOUGH THAT NEITHER OF US REALIZED WE HAD NOT CONTACTED THE TWR. IN DISCUSSING THE EVENT WITH THE CAPT; WE REALIZE THAT AT SUCH A CRITICAL POINT IN THE APCH IT MAY BE NECESSARY TO IGNORE REQUESTS FROM PAX UNTIL THE CRITICAL PHASE OF FLT IS COMPLETED. WE FURTHER REVIEWED THESE EVENTS WITH OUR COMPANY'S CHIEF PLT.