The National Aeronautics and Space Administration (NASA) is well-known for its excessive use of checklists. Over the history of this organization, checklists could be found placed all over its spacecraft, and covered everything from launch operations to spacewalk procedures and even to unlikely sudden multiple system failures. In fact, astronauts used so many checklists that Apollo 11 astronaut Michael Collins called his crew’s mission checklists the “fourth crew member.”
For the first few missions of a particular program (Apollo, Gemini, etc.) the astronauts have always been far less familiar with the checklists and standard procedures than the astronauts for later missions. This is because it was more likely that something unexpected would happen during the earlier missions, and the astronauts might need to “think on their feet” in order to stay alive.
In fact, it was somewhat common for the astronauts to modify their checklists “on the fly,” although they only did so reluctantly. Collins spoke about this reluctance during his post-flight briefing, saying “I don’t enjoy making changes to procedures. It seems like the crew only does that when they feel there’s some good need for it.”
Examples of NASA Checklist deviations:
Gemini 3 – the first manned Gemini mission, which had the primary goal of testing the new Gemini spacecraft. The astronauts deviated from the post landing checklist to accommodate for extra smoke from the thrusters.
Gemini 4 – the second manned Gemini mission, which included the first spacewalk by astronaut Edward H. White. Following White’s spacewalk the hatch initially failed to open, and the astronaut inside the capsule had to deviate from standard procedure in order help White to return to the spacecraft.
Mercury 9 – the last manned Mercury mission, in which the astronaut Gordon Cooper would remain in space for one full day. Electrical problems led to the failure of several systems, and as a result, Cooper prepared a revised checklist to finish his mission.
For Americans, checklists are guidelines more than fixed rules, and often are not taken very seriously. For example, NASA checklists are also places of amusement – for the Apollo 12 mission, the backup crew managed to sneak playboy pictures into the checklists which were attached to the wrists of the moonwalkers’ space suits.