Alexei Leonov, who would have originally commanded Soyuz 11, had advised the cosmonauts before the flight that they should manually close the valves between the orbital and descent modules as he did not trust them to shut automatically, a procedure he thought up during extensive time in the Soyuz simulator. However, Dobrovolsky, Volkov, and Patsayev either chose to disregard his warnings or else forgot about them during the lengthy mission. After the flight, Leonov went back and tried closing one of the valves himself and found that it took nearly a minute to do, too long in an emergency situation with the spacecraft's atmosphere escaping fast.