June 25, 1923  On Oct. 5, 1922, Lts. J.A. Macready and O.G. Kelly set a world endurance record of 35 hrs, 18 mins, 30 sec. in their T-2 airplane over San Diego for which they were awarded the Mackay Trophy. Had they not run low on gasoline, they could have remained in the air until personal fatigue or mechanical difficulty with the T-2 forced them to land.

To solve this fuel limitation problem, the flyers at Rockwell Field, San Diego, developed a system for mid-air refueling between D.H.4B airplanes. The first successful aerial refueling took place on June 25, 1923 when a D.H4B flying beneath it carrying Lts. L.H. Smith and J.P. Richter.