Like most other vehicles that are powered either by electricity or fuel, planes have limits to the range they can travel before they need refueling. This means that longer flights need to be planned around the amount of fuel an aircraft has available. In October 1922, two American lieutenants, John A. Macready and Oakley G. Kelley, set a record for remaining in air for a staggering 35 hours, 18 minutes, and 30 seconds. It was an impressive length of time, but it could have been even longer if the pair didn’t need to refuel.
This prompted a new strategy and on June 27, 1923, the first mid-air refueling took place thanks to developments from Rockwell Field in San Diego, California. The fuel was passed successfully by hose from one DH-4B to another. The practice was continuously tested, and on October 25, 1923, there was a successful flight from the Canadian border to the Mexican border without landing by way of three mid-air refueling sessions.
The ability to refuel while staying in the air not only gives pilots more longevity to get from one place to another, but it significantly increases flight safety by preventing many fuel-related emergency landings or crashes.