Narrative:

While on the lynsy 1 arrival into las, we were cleared to cross lynsy at 12000 ft and cleared the arrival. In the descent, I contacted las operations. I had been having problems with my CDU box so we had changed the primary radio to VHF #2 because I was having problems with VHF #1. During the time I was callings operations on VHF #1 (getting gate information, and talking to maintenance about my radio problems), I lost radio contact with operations. I initially thought it was my radio selector panel acting up again. After trying the radio several times, I realized the captain had started using VHF #1 as primary. I realized our mistake and swapped back to VHF #2 as primary. During this radio gaggle, we lost contact with approach. The captain continued on the approach, descending as depicted on the arrival. Company contacted us and gave us approach frequency and told us they were trying to get a hold of us. We contacted approach and notified them of our radio problems. Nothing was mentioned until we talked to ground. Ground told us to contact ATC. The captain talked with ATC and they said we were not cleared out of 12000 ft. The captain again called ATC when we got to lax. ATC checked the tapes and realized the captain twice said he was flying the arrival for which he thought he was cleared. ATC said they would not violate us because the controller missed the captain's readback. Supplemental information from acn 566571: I flew the lynsy 1 as depicted, descended as I thought we were cleared. Crossing mirok at or above 11000 ft and utare at 8000 ft. Upon landing, I was directed to contact las tower by phone where I learned for the first time of the altitude deviation. Tapes were checked and twice I had told controller that I was 'lynsy 1 profile descent' -- ZLA missed my improper readback and did not correct me to descend and maintain 12000 ft at lynsy. Departures at las were momentarily stopped until they got me back on frequency. He said I was off frequency for just over 5 mins. Because of the radio problems my first officer was experiencing, and his newness to our operation, I was monitoring both radios -- trying to assist him. I knew las was landing on runway 1L&right, but because of the note on the lynsy 1, that aircraft are 'to proceed via landing runway 25L until otherwise instructed by ATC,' I did not question in my mind, routing and altitudes on the arrival and was expecting the profile descent which led to my error. I did not realize that we had lost contact with las approach until I had already committed my error. IOE and radio difficulties were definitely contributors.

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Original NASA ASRS Text

Title: MULTIPLE DISTRS AND COM PROBS DURING ARR TO LAS VEGAS, NV, ON THE LYNSY RNAV 1 ARR LED TO TRACK AND ALTDEVS CAUSING DEPS TO BE STOPPED FOR A SHORT PERIOD OF TIME.

Narrative: WHILE ON THE LYNSY 1 ARR INTO LAS, WE WERE CLRED TO CROSS LYNSY AT 12000 FT AND CLRED THE ARR. IN THE DSCNT, I CONTACTED LAS OPS. I HAD BEEN HAVING PROBS WITH MY CDU BOX SO WE HAD CHANGED THE PRIMARY RADIO TO VHF #2 BECAUSE I WAS HAVING PROBS WITH VHF #1. DURING THE TIME I WAS CALLINGS OPS ON VHF #1 (GETTING GATE INFO, AND TALKING TO MAINT ABOUT MY RADIO PROBS), I LOST RADIO CONTACT WITH OPS. I INITIALLY THOUGHT IT WAS MY RADIO SELECTOR PANEL ACTING UP AGAIN. AFTER TRYING THE RADIO SEVERAL TIMES, I REALIZED THE CAPT HAD STARTED USING VHF #1 AS PRIMARY. I REALIZED OUR MISTAKE AND SWAPPED BACK TO VHF #2 AS PRIMARY. DURING THIS RADIO GAGGLE, WE LOST CONTACT WITH APCH. THE CAPT CONTINUED ON THE APCH, DSNDING AS DEPICTED ON THE ARR. COMPANY CONTACTED US AND GAVE US APCH FREQ AND TOLD US THEY WERE TRYING TO GET A HOLD OF US. WE CONTACTED APCH AND NOTIFIED THEM OF OUR RADIO PROBS. NOTHING WAS MENTIONED UNTIL WE TALKED TO GND. GND TOLD US TO CONTACT ATC. THE CAPT TALKED WITH ATC AND THEY SAID WE WERE NOT CLRED OUT OF 12000 FT. THE CAPT AGAIN CALLED ATC WHEN WE GOT TO LAX. ATC CHKED THE TAPES AND REALIZED THE CAPT TWICE SAID HE WAS FLYING THE ARR FOR WHICH HE THOUGHT HE WAS CLRED. ATC SAID THEY WOULD NOT VIOLATE US BECAUSE THE CTLR MISSED THE CAPT'S READBACK. SUPPLEMENTAL INFO FROM ACN 566571: I FLEW THE LYNSY 1 AS DEPICTED, DSNDED AS I THOUGHT WE WERE CLRED. XING MIROK AT OR ABOVE 11000 FT AND UTARE AT 8000 FT. UPON LNDG, I WAS DIRECTED TO CONTACT LAS TWR BY PHONE WHERE I LEARNED FOR THE FIRST TIME OF THE ALTDEV. TAPES WERE CHKED AND TWICE I HAD TOLD CTLR THAT I WAS 'LYNSY 1 PROFILE DSCNT' -- ZLA MISSED MY IMPROPER READBACK AND DID NOT CORRECT ME TO DSND AND MAINTAIN 12000 FT AT LYNSY. DEPS AT LAS WERE MOMENTARILY STOPPED UNTIL THEY GOT ME BACK ON FREQ. HE SAID I WAS OFF FREQ FOR JUST OVER 5 MINS. BECAUSE OF THE RADIO PROBS MY FO WAS EXPERIENCING, AND HIS NEWNESS TO OUR OP, I WAS MONITORING BOTH RADIOS -- TRYING TO ASSIST HIM. I KNEW LAS WAS LNDG ON RWY 1L&R, BUT BECAUSE OF THE NOTE ON THE LYNSY 1, THAT ACFT ARE 'TO PROCEED VIA LNDG RWY 25L UNTIL OTHERWISE INSTRUCTED BY ATC,' I DID NOT QUESTION IN MY MIND, ROUTING AND ALTS ON THE ARR AND WAS EXPECTING THE PROFILE DSCNT WHICH LED TO MY ERROR. I DID NOT REALIZE THAT WE HAD LOST CONTACT WITH LAS APCH UNTIL I HAD ALREADY COMMITTED MY ERROR. IOE AND RADIO DIFFICULTIES WERE DEFINITELY CONTRIBUTORS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.