By Veronika Bondarenko Airline plans to fly only one kind of plane in the future. There are many reasons an airline may want to operate a single type of plane — pilot training and route swaps are easier and you can save on not having too many different spare parts in stock. Having a single aircraft is a strategy typically taken on by smaller and low-cost airlines. Dallas-based Southwest (LUV) – Get Southwest Airlines Company Report flies exclusively the Boeing (BA) – Get The Boeing Company Report 737 while, in Europe, EasyJet (EJTTF) only takes city-hoppers on the Airbus (EADSF) A320s. While …