Narrative:

While on the arrival into ZZZ1, our flight received an ACARS message that our alternate had changed from ZZZ2 to ZZZ3. We had 6900 pounds of gas at the time and realized that we didn't have enough to accept our new alternate. The captain contacted dispatch and suggested a closer alternate, ZZZ4. The dispatcher sent us the WX which was a ceiling of 2300 ft and visibility of 8 mi. I was busy flying, we had a fuel low light on, approach was doing a runway change from xx to yy, and we were doing fuel low checklist. We landed without incident with 5400 pounds of gas. Later the dispatcher called and told captain that ZZZ4 was an illegal alternate because their ILS was down.

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Original NASA ASRS Text

Title: AN MD80 FLYING TO A LOW VISIBILITY DEST RECEIVED A LOW FUEL LIGHT WHILE MANEUVERING FOR AN APCH. DISPATCH ISSUED AN ILLEGAL ALTERNATE TO THE FLT WHILE AIRBORNE BECAUSE THE ORIGINAL ALTERNATE NO LONGER MET THE ALTERNATE REQUIREMENTS.

Narrative: WHILE ON THE ARR INTO ZZZ1, OUR FLT RECEIVED AN ACARS MESSAGE THAT OUR ALTERNATE HAD CHANGED FROM ZZZ2 TO ZZZ3. WE HAD 6900 LBS OF GAS AT THE TIME AND REALIZED THAT WE DIDN'T HAVE ENOUGH TO ACCEPT OUR NEW ALTERNATE. THE CAPT CONTACTED DISPATCH AND SUGGESTED A CLOSER ALTERNATE, ZZZ4. THE DISPATCHER SENT US THE WX WHICH WAS A CEILING OF 2300 FT AND VISIBILITY OF 8 MI. I WAS BUSY FLYING, WE HAD A FUEL LOW LIGHT ON, APCH WAS DOING A RWY CHANGE FROM XX TO YY, AND WE WERE DOING FUEL LOW CHKLIST. WE LANDED WITHOUT INCIDENT WITH 5400 LBS OF GAS. LATER THE DISPATCHER CALLED AND TOLD CAPT THAT ZZZ4 WAS AN ILLEGAL ALTERNATE BECAUSE THEIR ILS WAS DOWN.

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.