During the Congressional investigation, Senator Walter Mondale publicly revealed a NASA internal document citing problems with prime Apollo contractor North American Aviation, which became known as the Phillips Report.

AS-204 was to be the first crewed test flight of the Apollo command and service module (CSM) to Earth orbit, launched on a Saturn IB rocket.

In a spacecraft review meeting held with Shea on August 19, 1966 (a week before delivery), the crew expressed concern about the amount of flammable material (mainly nylon netting and Velcro) in the cabin, which both astronauts and technicians found convenient for holding tools and equipment in place.

[16]: 185 North American shipped spacecraft CM-012 to Kennedy Space Center on August 26, 1966, under a conditional Certificate of Flight Worthiness: 113 significant incomplete planned engineering changes had to be completed at KSC.

[19] Once all outstanding CSM-012 hardware problems had been fixed, the reassembled spacecraft completed a successful altitude chamber test with Schirra's backup crew on December 30.

[17]: 4–2  According to the final report of the accident investigation board, "At the post-test debriefing the backup flight crew expressed their satisfaction with the condition and performance of the spacecraft.

Grissom said in a February 1963 interview that NASA could not eliminate risk despite precautions:[21] An awful lot of people have devoted more effort than I can describe to [make] Project Mercury and its successors, as safe as humanly possible ...

[11] At 1:00 pm EST (18:00 GMT) on January 27, first Grissom, then Chaffee, and White entered the command module fully pressure-suited, and were strapped into their seats and hooked up to the spacecraft's oxygen and communication systems.

The stuck microphone was part of a problem with the communications loop connecting the crew, the Operations and Checkout Building, and the Complex 34 blockhouse control room.

All countdown functions up to the simulated internal power transfer had been successfully completed by 6:20 pm, and at 6:30 the count remained on hold at T minus 10 minutes.

The third phase began when most of the oxygen was consumed and was replaced with atmospheric air, essentially quenching the fire, but causing high concentrations of carbon monoxide and heavy smoke to fill the cabin, and large amounts of soot to be deposited on surfaces as they cooled.

The bodies were only able to be removed after 7.5 hours from the time the incident took place, due to the gasses and toxins present which prevented medical personnel from entering initially.

It declared, "It is NASA policy to investigate and document the causes of all major mission failures which occur in the conduct of its space and aeronautical activities and to take appropriate corrective actions as a result of the findings and recommendations.

[17]: 5–3 The board noted that a silver-plated copper wire, running through an environmental control unit near the center couch, had become stripped of its Teflon insulation and abraded by repeated opening and closing of a small access door.

In July, ASPO directed both North American and Grumman to ensure no silver or silver-coated electrical contacts existed in the vicinity of possible glycol spills in the Apollo spacecraft.

The pressure before launch was deliberately greater than ambient in order to drive out the nitrogen-containing air and replace it with pure oxygen, and also to seal the plug door hatch cover.

Also, while the system could easily vent the normal pressure, its flow capacity was utterly incapable of handling the rapid increase to 29 psi (200 kPa) caused by the intense heat of the fire.

First, a pure oxygen atmosphere is comfortably breathable by humans at 5 psi (34 kPa), greatly reducing the pressure load on the spacecraft in the vacuum of space.

Cosmonaut Valentin Bondarenko died on March 23, 1961, from burns sustained in a fire while participating in a 15-day endurance experiment in a high-oxygen isolation chamber, less than three weeks before the first Vostok crewed space flight; this was disclosed on January 28, 1986.

The spacecraft's environmental control system responded to the leaking air by adding more oxygen to the cabin, causing the concentration level to rise as high as 45%.

Seamans, Webb, Manned Space Flight Administrator Dr. George E. Mueller, and Apollo Program Director Maj Gen Samuel C. Phillips were called to testify before Anderson's committee.

[58] In the February 27 hearing, Senator Walter F. Mondale asked Webb if he knew of a report of extraordinary problems with the performance of North American Aviation on the Apollo contract.

[40] However, in late 1965, just over a year before the accident, Phillips had headed a "tiger team" investigating the causes of inadequate quality, schedule delays, and cost overruns in both the Apollo CSM and the Saturn V second stage (for which North American was also prime contractor).

[41] Mondale continued to refer to "the Report" despite Phillips' refusal to characterize it as such, and, angered by what he perceived as Webb's deception and concealment of important program problems from Congress, he questioned NASA's selection of North American as prime contractor.

Seamans later wrote that Webb roundly chastised him in the cab ride leaving the hearing, for volunteering information which led to the disclosure of Phillips' memo.

[58]: 11 Freshman Senators Edward W. Brooke III and Charles H. Percy jointly wrote an Additional Views section appended to the committee report, chastising NASA more strongly than Anderson for not having disclosed the Phillips review to Congress.

Mondale wrote his own, even more strongly worded Additional View, accusing NASA of "evasiveness, ... lack of candor, ... patronizing attitude toward Congress ... refusal to respond fully and forthrightly to legitimate Congressional inquiries, and ... solicitous concern for corporate sensitivities at a time of national tragedy".

[58]: 16 The potential political threat to Apollo blew over, due in large part to the support of President Lyndon B. Johnson, who at the time still wielded a measure of influence with the Congress from his own Senatorial experience.

[74] The "Dedicated to the living memory of the crew of the Apollo 1" plaque is quoted at the end of Wayne Hale's Requiem for the NASA Space Shuttle program.

KSC's Visitor Complex also houses memorials that include parts of Challenger and Columbia, located in the Space Shuttle Atlantis exhibit.