Recently, M posted:

For some strange reason, he never allows his fuel to run
down lower than a one hour reserve anymore.


Although this is a reasonable approach to fuel management, it's not
the most professional approach, nor does it allow the maximum utility
of one's aircraft. A competent pilot should, under certain
circumstances, land his plane with 30 minute fuel remaining, and do
so safely without anxiety.

It requires a complete confidence of fuel burn, which can only come
from many hours of operation of the exact same aircraft and proper
leaning procedure under all conditions and power setting. It requires
very detailed planning, because weather plays a significant role in
determining fuel reserve. It also requires a continuous re-evaluation
of weather and fuel situations in-flight, because weather can change
unexpectedly in a long flight that can affect what a safe fuel reserve
is. Last, it requires a clear alternative of what to do if something
unexpected happen at the destination runway: what if the runway you
intend to land become unavailable right when you approach the airport
with 30 minute fuel in the tank?

With all that, it is possible to plan a flight with 30 minute fuel
reserve. However it's just not possible to do this safely with a
unfamiliar aircraft.

I question this scenario as you've presented it. As you've pointed out,
the weather plays a large part in fuel burn over a distance. Landing your
plane with 30 minutes reserve fuel presumes that when you've travelled x.y
hours at a particular burn rate, the airport is right under you. Chances
are good that will not be the case, and you will wind up with either more
or less than 30 minutes fuel remaining.

Also as you've pointed out, another consideration is that accurate leaning
is important to precise fuel burn. However, as GA mixture controls lack
precise calibration, one of the few other ways to know your fuel
consumption would be with a fuel flow meter. Many planes are not so
equipped, and if the plane you fly is one of those, then it doesn't really
matter whether you own it or not; you're making a guess about the
precision based on past experience, possibly against RPM.

Lastly, how much fuel should be remaining at your destination may be
better determined by how much additional fuel might be needed if there is
some unexpected problem at the destination. I wouldn't want to have 30
minutes remaining at the destination if the alternative is 45 minutes
away. ;-)

Regards, happy holidays and safe flying!

Neil