How was the B-17 prototype lost?

Short answer

The Model 299 stalled and spun into the ground shortly after takeoff, and caught fire, during a test flight scheduled for October 30, 1935. Post-accident interviews with Tower and Putt determined that the gust lock on the control surfaces had not been released. Hill and Tower died.

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

Sunset silhouette of flying fortress, Langley Field, Va

A flight to measure the rate of climb

The Model 299 first flew on July 28, 1935, with Boeing's chief test pilot, Leslie Tower, at the controls. On October 30, 1935, a test flight was scheduled to determine the rate of climb and service ceiling. The pilot in command was Major Ployer Peter Hill, chief of the Flying Branch of the Material Division at Wright Field, on his first flight in the Model 299. The copilot was Lieutenant Donald L. Putt, with Tower behind the pilots in an advisory role.

Stalling on takeoff

The aircraft stalled and spun into the ground shortly after takeoff, and caught fire. Post-accident interviews with Tower and Putt determined that the gust lock on the control surfaces had not been released. Hill, who initially survived the impact, died within hours, and Tower on November 19.

The origin of the written checklist

According to Doyle, the loss of Hill and Tower, and of the Model 299 itself, was the direct cause of the creation of the modern written checklist that pilots use today.