In Pocket Planes, XP stands for eXperience Points and is based on the coins and bux that you earn in the game.
Whenever one of your planes lands in an airport after delivering passengers and cargo on its flight, you are awarded XP according to the following formula:
XP = C + P + (500 * B) + (2 * (B - 1))
C = Total number of coins awarded for delivered cargo
P = Total number of coins awarded for delivered passengers
B = Total number of bux awarded for delivered items
XP For Coins In Air
While a plane is in flight, you can view the plane by clicking it in your airplane list. While it flies through the air, coins and bux randomly fly past. You can take the coins and bux by tapping them.
You are not awarded XP for bux that you tap in mid-air, but you do receive XP for coins that you tap in mid-air.
Earning More XP
As you can see from the formula above, you get a bonus for delivering items that award bux instead of coins. Therefore, if you want to earn more XP, you should deliver as many bux items as possible.
Losing Money Does Not Lose XP
If a flight is going to lose money, you will NOT lose any XP. You will lose coins, but your XP is not reduced when this happens.