The Flight of the Model 299
In the mid-1930s, the United States Army Air Corps held a competition for a new long-range bomber. Boeing's entry, the Model 299 (the prototype for the legendary B-17 Flying Fortress), was an engineering marvel. It featured four engines instead of two, could carry a payload twice as far as its competitors, and flew faster than previous bombers.
Major Ployer P. Hill, one of the Air Corps' most experienced test pilots, took the controls at Wright Field in Ohio. As the massive aircraft thundered down the runway, it lifted off cleanly. But at 300 feet, the plane suddenly pitched sharply upward, stalled, and crashed in a fiery explosion. Major Hill and one other crew member were killed.
The Pilot Error That Changed History
The subsequent investigation revealed a chilling truth: there was absolutely nothing wrong with the aircraft.
The Model 299 was incredibly complex. The pilot had to manage four engines, a retractable landing gear, new wing flaps, electric trim tabs, and constant-speed propellers. While distracted by this massive cognitive load, Major Hill forgot one simple step: he failed to release the elevator and rudder gust locks (mechanisms that kept the control surfaces from blowing in the wind while parked).
Newspapers at the time declared the giant plane "too much airplane for one man to fly." The Air Corps nearly cancelled the contract entirely, a decision that would have drastically altered the outcome of World War II.
Engineering Human Reliability
Boeing engineers refused to accept that human limitations meant the end of the bomber program. If the plane was too complex for memory alone, they needed to offload the cognitive burden. They created a radically simple intervention: a step-by-step checklist.
Unlike a training manual, this wasn't designed to teach a pilot how to fly. It was a DO-CONFIRM tool designed for experts to verify that crucial, easily forgotten steps were completed. The checklist was broken down into distinct phases of flight: Before Starting, Before Takeoff, Before Landing, and After Landing.
With the checklist in hand, pilots went on to fly the B-17 for 1.8 million miles without a single accident. The aviation checklist was born, and the B-17 became the decisive bomber of the European theater.