Since the popularity of charter jets is increasing, the offering of one-way flights is becoming more popular as well. Charter jet companies will often quote a customer the price of chartering a jet for a one-way flight due to the ability of that company to charter the jet back to its origin with a new customer. This also allows for the client to travel between different airports or cities while having time to relax in between. If a CEO of a company has to make rounds to different areas of the country might want to spend a week in each place. One-way trips allow him to do so at an affordable price. Otherwise the cost of parking a charter jet on the airport for the time it would take that CEO to complete his business and move on could in some cases be more then the actual price of chartering the jet.
When talking about a more commercialized aviation industry (relating to the airlines) one-way flights can cost the client more then what is affordable. An airline has more invested in flying from one place to another. It can cost more fuel to climb, taxi, decend then during the entire cruise portion of flight. Airlines don’t sell seats on their gigantic turbo-jets to make a profit they sell seats to cover their cost. A client wanting only a one way ticket does not guarantee the airline a return passage and thus the airline is reluctant to sell the ticket for a cheaper price. They want a customer who is going to fly their airline more then one. So typically a one-way ticket will cost almost as much if not more then a round trip ticket.
Another common meaning for one-way in aviation is the direction of flight. In the aviation world there are airways defined by magnetic or satellite plotted courses in which aircraft fly. Certain airways are designated as one-direction flight airways much like a one-way street. These airways can be one-way flight all the time or they can be designated as such only during certain hours of the day. One-way airways can be two-way traffic but with one-way traffic designated to a particular side of the airway just like a two-way street.