I got this article from a fellow pilot. It is a great explanation about the use of airplanes in missions.

About the Cost of the Expansion of God’s Kingdom in the Amazon Basin—In response to the assertion that the use of airplanes is too expensive and difficult

Question: If we are to be obedient to Christ’s command to make disciples of all peoples does that include the river people of the Basin who live in remote and isolated places, including the tens of thousands living in communities of less than half a dozen families often isolated from one another by great distances on our hundreds, even thousands, of rivers, streams, and lakes in the Amazon jungle?

For most of those people there are only two methods of transportation open to disciples who desire to make disciples of their Lord and King—if they are to get to where the river people live. They can get there by boats in all their various forms or airplanes capable of landing and taking off on the water.

Question: Aren’t boats significantly cheaper and easier to operate? There is an appropriate analogy with our cars. They may be if the destination is close by, but when the destinations we need to travel to become farther and farther away we tend to park our cars. Why? One reason is because we are no longer only considering the cost of fuel and maintenance, but other things like food and lodging. And, in the Amazon Basin the distance on the river can easily be twice or even three times the straight line distance by air because of the way our rivers wind and double back on themselves.

But there is generally another more important factor that has come into the picture—TIME. The money we were afraid to spend, but did, often acts like an investment and, though we could not anticipate how it might happen when the money left our hands—comes back to us—is somehow recovered, but “time” never does. It is unrecoverable. Once we have spent it, it is gone and a few have realized that this makes “time” one of the most precious things we have and we need to spend it well and use it wisely. In the Amazon Basin a day of travel on the river is roughly equal to an hour in one of our planes and an hour in a boat equal to mere minutes in a plane.

There is another factor that now almost seems like some kind of law of missions: The greater is the distance and the time it will take to get to an already scheduled mission objective, whatever it may be, the less likely it will actually happen when the time comes to go. But change one of those factors—in this case the time it takes to get there—a positive outcome is much much more likely.

A related mission law is this: It is much more difficult to make disciples where we don’t go.