Running dry?

"Neil Gould" wrote:

I also think landing with 30 minutes of fuel is too little. So, how
much is enough? Let's assume we can agree on an hour, which in a 180
HP PA-28 means about 8 gallons. You take off with 48 usable and fly
for 5 hours, leaving an estimated 8 gallons left. Which is a more
useful configuration to have at this point, an estimated 4 gallons
usable remaining in each tank, or an estimated 8 gallons usable in
one tank and the other one dry?

I would feel more comfortable with 4 in each tank than with a dry tank.

Let's examine that. We're comparing the relative risk of two events.

Event 1 is that the fuel selector valve fails when you go to switch to the
tank containing the remaining 8 gallons.

Event 2 is that your estimate of how much fuel is left in the tank is wrong
by 4 gallons (16%).

Which is more likely?

Recently, Roy Smith posted:

"Neil Gould" wrote:

I would feel more comfortable with 4 in each tank than with a dry
tank.

Let's examine that. We're comparing the relative risk of two events.

Event 1 is that the fuel selector valve fails when you go to switch
to the tank containing the remaining 8 gallons.

Event 2 is that your estimate of how much fuel is left in the tank is
wrong by 4 gallons (16%).

Which is more likely?

Talk about straw men! If the *only* risk in running a tank dry in flight
was the fuel selector valve failing -- probably the *least* likely thing
to happen -- there wouldn't be much point in this discussion, would there?
Yet, a variant on the "least likely thing to happen" happened to me in
flight. OTOH, my fuel consumption estimates have NEVER been off by 4
gallons (which is closer to between 20-25% in the planes that I fly, btw).
So, what can be concluded from this data? IMO, nada.

I recently read an article by a pilot that ferries aircraft between Hawaii
and Australia. Part of his prep was to test actual fuel flow in flight,
because the jump would necessitate reliance on the reserves. He didn't
mention doing it by running a tank dry in flight.

In the flying that I do, there is no direction that I can go where there
isn't fuel well within the range of the plane's fuel capacity without
considering reserves. So, I plan accordingly. You can fly however you
wish. I just see no point in unnecessarily pushing limits.

Regards,

Neil