the aft equipment bay. CM-119 was fitted with two jump seats as a Skylab Rescue vehicle, which was never used. Major differences between Block I and Block II Command module The Block II used a one-piece, quick-release, outward opening hatch instead of the two-piece plug hatch used on Block I, in which the inner piece had to be unbolted and placed inside the cabin in order to enter or exit the spacecraft (a flaw that doomed the Apollo 1 crew). The Block II hatch could be opened quickly in case of an emergency. (Both hatch versions were covered with an extra, removable section of the Boost Protective Cover which surrounded the CM to protect it in case of a launch abort.) The Block I forward access tunnel was smaller than Block II, and intended only for emergency crew egress after splashdown in case of problems with the main hatch. It was covered by the nose of the forward heat shield during flight. Block II contained a shorter forward heat shield with a flat removable hatch, beneath a docking ring and probe mechanism which captured and held the LM. The aluminized PET film layer, which gave the Block II heat shield a shiny mirrored appearance, was absent on Block I, exposing the light gray epoxy resin material, which on some flights was painted white. The Block I VHF scimitar antennas were located in two semicircular strakes originally thought necessary to help stabilize the CM during reentry. However, the uncrewed reentry tests proved these to be unnecessary for stability, and also aerodynamically ineffective at high simulated lunar reentry speeds. Therefore, the strakes were removed from Block II and the antennas were moved to the service module. The Block I CM/SM umbilical connector was smaller than on Block II, located near the crew hatch instead of nearly 180 degrees away from it. The separation point was between the modules, instead of the larger hinged arm mounted on the service module, separating at the CM sidewall on Block II. The two negative pitch RCS engines located in the forward compartment were arranged vertically on Block I, and horizontally on Block II. Service module On the Apollo 6 uncrewed Block I flight, the SM was painted white to match the command module's appearance. On Apollo 1, Apollo 4, and all the Block II spacecraft, the SM walls were left unpainted except for the EPS and