Narrative:

On phx/las scheduled air carrier flight. Numerous thunderstorm cells over entire route as was forecasted and noted on radar before departure. Only slight deviations required to avoid. On descent in pgs area received numerous speed changes and delay vectors from ZLA and las approach. Through 17000 ft penetrated some light precipitation (on our airborne radar) which actually was moderate to heavy with accompanying moderate turbulence. Las ATIS was giving runway 25L as the approach with winds variable less than 10000 ft good ceiling and visibility. When we were about 20 mi out approach reported moderate to heavy rain over the airport and LLWS. There was extensive lightning in area. Airport was visible through 11000 ft. Approach then started vectoring traffic for runways 1, we were still quite high on a southwest heading when cleared for a visual to runway 1R. Because I was using speed brakes for descent I kept bank angle minimal, flew through the extended ctrlines and intercepted on a northeast heading. At this point the tower asked 'will you be able to get down for runway 1L?' we acknowledged in the affirmative, and landed runway 1L with no problem. On rollout tower advised 'you were cleared to land runway 1R.' we both assumed a 'clearance to land' from the previous query but I was remiss for not confirming a landing clearance change. We both thought we'd understood runway 1L was our runway. We had a good sight picture for runway 1L. The tower was giving multiple slowing and delay vectors. Aircraft were requesting holding, tower replied 'we are unable, there is no place to hold because of the rapidly deteriorating WX.' our own radar was apparently malfunctioning as we now had a 'WX radar weak' EICAS message so we had a clearance to land on runway 1L (we thought). Rapidly changing WX conditions and degraded radar capability, we landed, as cleared. At no time was this flight in jeopardy of any kind. At no time was safety compromised in any way. After touchdown moderate to heavy rain commenced. A couple of points: runway 1L was HIRL, runway 1R only MIRL. No precision electronic guidance for either runway. ATC did a commendable job under very rapidly changing conditions.

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Original NASA ASRS Text

Title: AN ACR FLC FLYING B757 INTO LAS BECOMES DISTRACTED WHEN DEVIATING FOR WX AND LANDS ON THE WRONG RWY.

Narrative: ON PHX/LAS SCHEDULED ACR FLT. NUMEROUS TSTM CELLS OVER ENTIRE RTE AS WAS FORECASTED AND NOTED ON RADAR BEFORE DEP. ONLY SLIGHT DEVS REQUIRED TO AVOID. ON DSCNT IN PGS AREA RECEIVED NUMEROUS SPD CHANGES AND DELAY VECTORS FROM ZLA AND LAS APCH. THROUGH 17000 FT PENETRATED SOME LIGHT PRECIPITATION (ON OUR AIRBORNE RADAR) WHICH ACTUALLY WAS MODERATE TO HVY WITH ACCOMPANYING MODERATE TURB. LAS ATIS WAS GIVING RWY 25L AS THE APCH WITH WINDS VARIABLE LESS THAN 10000 FT GOOD CEILING AND VISIBILITY. WHEN WE WERE ABOUT 20 MI OUT APCH RPTED MODERATE TO HVY RAIN OVER THE ARPT AND LLWS. THERE WAS EXTENSIVE LIGHTNING IN AREA. ARPT WAS VISIBLE THROUGH 11000 FT. APCH THEN STARTED VECTORING TFC FOR RWYS 1, WE WERE STILL QUITE HIGH ON A SW HEADING WHEN CLRED FOR A VISUAL TO RWY 1R. BECAUSE I WAS USING SPD BRAKES FOR DSCNT I KEPT BANK ANGLE MINIMAL, FLEW THROUGH THE EXTENDED CTRLINES AND INTERCEPTED ON A NE HEADING. AT THIS POINT THE TWR ASKED 'WILL YOU BE ABLE TO GET DOWN FOR RWY 1L?' WE ACKNOWLEDGED IN THE AFFIRMATIVE, AND LANDED RWY 1L WITH NO PROB. ON ROLLOUT TWR ADVISED 'YOU WERE CLRED TO LAND RWY 1R.' WE BOTH ASSUMED A 'CLRNC TO LAND' FROM THE PREVIOUS QUERY BUT I WAS REMISS FOR NOT CONFIRMING A LNDG CLRNC CHANGE. WE BOTH THOUGHT WE'D UNDERSTOOD RWY 1L WAS OUR RWY. WE HAD A GOOD SIGHT PICTURE FOR RWY 1L. THE TWR WAS GIVING MULTIPLE SLOWING AND DELAY VECTORS. ACFT WERE REQUESTING HOLDING, TWR REPLIED 'WE ARE UNABLE, THERE IS NO PLACE TO HOLD BECAUSE OF THE RAPIDLY DETERIORATING WX.' OUR OWN RADAR WAS APPARENTLY MALFUNCTIONING AS WE NOW HAD A 'WX RADAR WEAK' EICAS MESSAGE SO WE HAD A CLRNC TO LAND ON RWY 1L (WE THOUGHT). RAPIDLY CHANGING WX CONDITIONS AND DEGRADED RADAR CAPABILITY, WE LANDED, AS CLRED. AT NO TIME WAS THIS FLT IN JEOPARDY OF ANY KIND. AT NO TIME WAS SAFETY COMPROMISED IN ANY WAY. AFTER TOUCHDOWN MODERATE TO HVY RAIN COMMENCED. A COUPLE OF POINTS: RWY 1L WAS HIRL, RWY 1R ONLY MIRL. NO PRECISION ELECTRONIC GUIDANCE FOR EITHER RWY. ATC DID A COMMENDABLE JOB UNDER VERY RAPIDLY CHANGING CONDITIONS.

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.