In Pocket Planes you have an option to upgrade your planes. Upgrading planes can increase their range, increase their speed, and decrease their weight. Increasing a plane's range will allow it to fly farther without having to stop at an airport for fuel. Increasing a plane's speed will make flights take less time, but this does add a slight increase to the price of flying (like 6 coins). Decreasing a plane's weight will increase your profit by reducing the cost to fly per mile. Each aspect can be upgraded 3 times per plane. Upgrades cost 
, meaning you will need to consider whether or not the plane in question really needs the upgrades. The price of an upgrade does not increase with each level, though it differs from plane to plane. An upgrade always costs the same amount of as buying one part of the plane.