- Project Mercury (U.S.),
- Space flight -- Human factors,
- Space suits -- Safety measures
Audiovisual records of a Project Mercury pilot's activities during an orbital flight indicate that his visor was left open during reentry and descent to the sea surface, phases of flight during which cabin pressure loss was to be mitigated by suit pressurization; however the suit could not have been pressurized with the visor open. Thus, for a presently unknown reason, a critical safety step—sealing the visor and making a pressure suit integrity test before re-entry—was overlooked in this flight, a fact itself unreported in any flight review or historical documents known to the author. The lesson is clear: even a highly-motivated, federally-funded project remains at base a collaboration of individuals, the project only being as strong as the proverbial weakest link. Attention to development of thorough and unambiguous procedural checklists is reiterated.