What is the heel of a gas tank?

The heel of a gas tank refers to the lowest part of the tank where fuel can accumulate due to gravity. It is often designed to collect any remaining fuel that may not be accessible to the fuel pump, helping to ensure that as much fuel as possible is used before refueling. In aviation, the heel can also refer to the last bit of fuel that is left in the tank, which may not be usable for flight. Proper management of the heel is important for efficiency and safety in fuel systems.