Apollo 13 more immediate and visible warnings of anomalies. Because Apollo 13 followed the free-return trajectory, its altitude over the lunar far side was approximately greater than the orbital altitude on the remaining Apollo lunar missions. The Moon was almost at apogee during the mission (as it also was during the flights of Apollo 10 and Apollo 15), which also increased the distance from the Earth. The combination of the two effects ensures that Apollo 13 holds the absolute altitude record for a manned spacecraft, reaching a distance of from Earth on 7:21 pm EST, April 14, 1970. The A7L spacesuit intended
Apollo program landings. The S-IC first stage burned RP-1/LOX for a rated thrust of , which was upgraded to . The second and third stages burned liquid hydrogen, and the third stage was a modified version of the S-IVB, with thrust increased to and capability to restart the engine for translunar injection after reaching a parking orbit. NASA's Director of Flight Crew Operations during the Apollo program was Donald K. "Deke" Slayton, one of the original Mercury Seven astronauts who was medically grounded in September 1962 due to a heart murmur. Slayton was responsible for making all Gemini and Apollo crew assignments.