Funny thing is - I have two cars with digital fuel injection management.
On both of them the fuel consumption average is extremely accurate. (2% error)
This measured over tens of thousands of kilometres. As an example of how common
this is these days - even my Renault Scenic was reliable (At least the fuel/trip
computer part was)

When my car says - X distance to empty tank, or X litres remaining - I tend to
believe it...

Conversely the power loading on an aircraft and the distance through the air
between two points on the map, can vary considerably over even short periods. So
while "Distance remaining" is unlikely to be available, it must be possible to
build an accurate "fuel used" calculator. If you could get an accurate gauge you
would then be able to derive an accurate "Time remaining at current power
setting" metric. Problem is the bit about digital fuel injector system - it
KNOWS how much fuel it injected and only checks the float for a "sanity" check -
the stuff they generally attach to the prehistoric things behind the propeller
on the average spam can is basically a graduated fuel leak, so you would be
entirely reliant on the float and sender unit. The only time these are
relatively accurate is on level ground without agitation. Many (most?) aircraft
are not refuelled in a flying attitude so the initial reading is inaccurate,
then in flight the wet stuff is sloshing around - challenging to read accurately
with a float. Which is why sight gauges are so popular - and the accurate light
aircraft fuel gauge is an oxymoron.

Wait - I did see one that worked very well once - a paint graduated wire with a
cork on it in a Pietenpol Aircamper - if the little red knob on the end of the
wire reached the top of the cowling you were about one minute away from becoming
a glider - which is the preferred method of flight.

Michael Ash wrote:
J a c k wrote:
Ian wrote:

I am amazed that nobody seems to have come up with a really reliable
fuel gauge for light aircraft. I know it's a fairly small market, but
aviation prices are high: I'd have thought it would be worth
somebody's time.
Why? The flight manual and a stick, verified by experience, work very well.

Inaccurate gauges are not the cause of the problem.

Do you, or anyone else, schedule fuel stops for your car by taking its
average miles per gallon (or hours per gallon) and multiplying it by the
length of your trip, all the while ignoring that terrible imprecise fuel
guage? Personally I just drive around until the thing is around the red
area that says "you're getting close", then I stop for fuel. When I'm
going to go through an area where fuel is scarce, I will stop if the guage
is higher. Trying to calculate the fuel burn from first principles seems
like the sort of thing that's likely to leave me stranded in the mountains
with no gas. Why doesn't this work for aircraft? (He asks, as a glider
pilot with no power rating.)