The Walter motor stalled about 15 seconds after take-off. It is estimated the Natter reached , at which point it nose-dived and hit the ground with great force about 32 seconds later, some kilometres from the launch site. Unknown at the time, one of the Schmidding boosters failed to jettison and its remains were dug up at the crash site in 1998. The pilot was likely unconscious long before the crash. Bachem surmised Sieber had involuntarily pulled back on the control column under the effect of the 3 G acceleration. Examination of the canopy, which fell near the launch site, showed the tip of the latch was bent, suggesting it may not have been in the fully closed position at launch. The pilot's headrest had been attached to the underside of the canopy and as the canopy flew off the pilot's head would have snapped back suddenly about , hitting the solid wooden rear upper cockpit bulkhead, and either knocking Sieber unconscious or breaking his neck. The accident reinforced Bachem's long held belief that the take-off and flight in the vicinity of the target bombers should be fully automated. The canopy latch was strengthened and the headrest was attached to the backboard of the cockpit. Before the introduction of the autopilot in the test programme, the control column would have a temporary locking device on it, which would allow the machine to ascend vertically to at least and then be removed by the pilot. The Walter motor probably ceased operation because the Natter was virtually upside-down and air may have entered the intake pipes in the propellant tanks, starving the motor. Sieber had become the first man to take off vertically from the ground under pure rocket power, 16 years before Yuri Gagarin's "Vostok 1" pioneering, peacetime orbital flight. Following Sieber's death, several pilots offered to take his place, and three more manned launches were performed in quick succession. The RLM now decided that the Natter had displayed an acceptable standard of reliability to warrant operational evaluation, and preparations were made for 10 fully armed aircraft at Kirchheim, near Stuttgart. The SS ordered 150 Natters, and the "Luftwaffe" ordered 50, but none were delivered by the end of the war. Much debate has surrounded the number of Natters built at the Bachem-Werk and their disposition. According to Bachem, 36 "Natters" were produced at the Bachem-Werk in Waldsee by the end of the war. Up to April 1945, 17 aircraft had been used in unmanned trials comprising five gliders, all slung under an He 111 in the "Mistelschlepp" configuration prior to launch, and 12 VTO examples.