Narrative:

Declared 'emergency fuel' during unplanned diversion to las. Flight required to divert to las due to unforecast dust storm rapidly and dramatically reducing visibility at phx. Flight released to phx with scheduled fuel load of 11000 pounds, including standard reserve of 4000 pounds plus 1200 pounds of 'extra fuel.' current and forecast WX for phx was for VFR conditions with no hazards noted. Obtained ATIS WX at top of descent. WX was calm winds, 10 SM visibility, circuit breaker, 150 sct, 250 sct. As descent continued, approach control began issuing airspeed adjustments and delay vectors due to dust storm north of airport. Discussed situation with flight dispatcher on company radio. Approximately 5 mins later the situation had deteriorated. We were advised that we were #12 in the approach sequence and that phx had become IFR for blowing dust. As a new captain on the A320 my minimums were 1 mi or RVR 4500. Visibility was dropping rapidly. The dispatcher and I agreed a divert back to las was in order. Upon reaching cruise altitude, I first declared 'minimum fuel,' then to ensure priority handling, I declared 'emergency fuel.' our onboard FMGS computed a landing fuel of 1200 pounds at las. An uneventful approach and landing was made at las. Shutdown at gate with 1060 pounds.

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Original NASA ASRS Text

Title: AN A320 FLC ENCOUNTERED UNFORECAST WX AND DECLARED A FUEL EMER FOR LNDG AT LAS.

Narrative: DECLARED 'EMER FUEL' DURING UNPLANNED DIVERSION TO LAS. FLT REQUIRED TO DIVERT TO LAS DUE TO UNFORECAST DUST STORM RAPIDLY AND DRAMATICALLY REDUCING VISIBILITY AT PHX. FLT RELEASED TO PHX WITH SCHEDULED FUEL LOAD OF 11000 LBS, INCLUDING STANDARD RESERVE OF 4000 LBS PLUS 1200 LBS OF 'EXTRA FUEL.' CURRENT AND FORECAST WX FOR PHX WAS FOR VFR CONDITIONS WITH NO HAZARDS NOTED. OBTAINED ATIS WX AT TOP OF DSCNT. WX WAS CALM WINDS, 10 SM VISIBILITY, CB, 150 SCT, 250 SCT. AS DSCNT CONTINUED, APCH CTL BEGAN ISSUING AIRSPD ADJUSTMENTS AND DELAY VECTORS DUE TO DUST STORM N OF ARPT. DISCUSSED SIT WITH FLT DISPATCHER ON COMPANY RADIO. APPROX 5 MINS LATER THE SIT HAD DETERIORATED. WE WERE ADVISED THAT WE WERE #12 IN THE APCH SEQUENCE AND THAT PHX HAD BECOME IFR FOR BLOWING DUST. AS A NEW CAPT ON THE A320 MY MINIMUMS WERE 1 MI OR RVR 4500. VISIBILITY WAS DROPPING RAPIDLY. THE DISPATCHER AND I AGREED A DIVERT BACK TO LAS WAS IN ORDER. UPON REACHING CRUISE ALT, I FIRST DECLARED 'MINIMUM FUEL,' THEN TO ENSURE PRIORITY HANDLING, I DECLARED 'EMER FUEL.' OUR ONBOARD FMGS COMPUTED A LNDG FUEL OF 1200 LBS AT LAS. AN UNEVENTFUL APCH AND LNDG WAS MADE AT LAS. SHUTDOWN AT GATE WITH 1060 LBS.

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.