Because B-17s were in short supply, the pilots trained on Douglas B-18 Bolos and Northrop A-17s, as well as Stearman PT-17 biplanes. Under the command of Lt. Colonel Eugene Eubank, the 19th Bombardment Group focused on precision, high-altitude, and formation flying. They also flew mock attacks on New Mexico villages and ranches. Eubank was known for being a taskmaster, demanding that his pilots gain extensive cockpit experience and that the men cross-train as navigators and bombardiers. As such, it was purported that every B-17 flight had a half-dozen pilots aboard, two flying, two practicing dead reckoning and celestial navigation, and two making practice bomb runs.