AC50 flight crew departs with enough reserves for a VFR flight but ends up diverting due to unforeca...

Attributes
ACN	787319
Time
Date	200805
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 3000
Environment
Flight Conditions	IMC
Weather Elements	Thunderstorm Rain
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : charter
Make Model Name	Commander 500
Operating Under FAR Part	Part 135
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : charter
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 75 flight time total : 415 flight time type : 55
ASRS Report	787319
Events
Anomaly	inflight encounter : weather non adherence : company policies
Independent Detector	other flight crewa
Resolutory Action	flight crew : diverted to another airport
Supplementary
Problem Areas	Weather Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Company policy was not taken into consideration and we took off with less than 90 gallons of fuel. During the flight; the crew was unaware that the fuel gauges read inaccurate under 50 gallons. The fuel truck was inoperative at ZZZ and we did not have contracted prices for fuel. The decision was made by the PIC to take off and refuel at our next stop. Reserves were adequate for the flight and no alternate was needed due to the forecast. About 40 mi out a thunderstorm cell had popped up; this along with unforecasted winds gave us a problem. Instead of a crosswind; we had a headwind; and this only became more evident as we got closer. It became obvious that ATC wanted to vector us and clearly we did not think we had the fuel for that operation. We made the decision to divert to get down safely in VMC. We got indicated low into our reserves and we decided to declare a fuel emergency. Landing safely; topping off; and talking to the company; we later realized that the fuel gauge indicated incorrectly. Too much emphasis and trust was put into our fuel gauge instead of trusting our flight planning.

Original NASA ASRS Text

Title: AC50 FLT CREW DEPARTS WITH ENOUGH RESERVES FOR A VFR FLT BUT ENDS UP DIVERTING DUE TO UNFORECAST WEATHER ENROUTE AND ASSOCIATED ATC VECTORS.

Narrative: COMPANY POLICY WAS NOT TAKEN INTO CONSIDERATION AND WE TOOK OFF WITH LESS THAN 90 GALLONS OF FUEL. DURING THE FLT; THE CREW WAS UNAWARE THAT THE FUEL GAUGES READ INACCURATE UNDER 50 GALLONS. THE FUEL TRUCK WAS INOP AT ZZZ AND WE DID NOT HAVE CONTRACTED PRICES FOR FUEL. THE DECISION WAS MADE BY THE PIC TO TAKE OFF AND REFUEL AT OUR NEXT STOP. RESERVES WERE ADEQUATE FOR THE FLT AND NO ALTERNATE WAS NEEDED DUE TO THE FORECAST. ABOUT 40 MI OUT A TSTM CELL HAD POPPED UP; THIS ALONG WITH UNFORECASTED WINDS GAVE US A PROB. INSTEAD OF A XWIND; WE HAD A HEADWIND; AND THIS ONLY BECAME MORE EVIDENT AS WE GOT CLOSER. IT BECAME OBVIOUS THAT ATC WANTED TO VECTOR US AND CLEARLY WE DID NOT THINK WE HAD THE FUEL FOR THAT OP. WE MADE THE DECISION TO DIVERT TO GET DOWN SAFELY IN VMC. WE GOT INDICATED LOW INTO OUR RESERVES AND WE DECIDED TO DECLARE A FUEL EMER. LNDG SAFELY; TOPPING OFF; AND TALKING TO THE COMPANY; WE LATER REALIZED THAT THE FUEL GAUGE INDICATED INCORRECTLY. TOO MUCH EMPHASIS AND TRUST WAS PUT INTO OUR FUEL GAUGE INSTEAD OF TRUSTING OUR FLT PLANNING.

Data retrieved from NASA's ASRS site as of May 2009 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.

AC50 flight crew departs with enough reserves for a VFR flight but ends up diverting due to unforecast weather enroute and associated ATC vectors.