 The second row had PROP, responsible for the propulsion system; GNC, responsible for systems that determine the spacecraft's attitude and issue commands to control it; MMACS (pronounced "max"), responsible for the mechanical systems on the space craft, such as the payload bay doors and landing gear; and EGIL (pronounced "eagle"), responsible for the fuel cells, electrical distribution and O2 & H2 supplies.The third row had DPS, responsible for the computer systems; ACO or Payloads, responsible for all payload-related activities (depending on whether the shuttle flight supported an ISS assembly flight or not; FAO, responsible for the overall plans of activities for the entire flight; and EECOM responsible for the management of environmental systems.The fourth row had INCO, responsible for communications systems for uploading all systems commands to the vehicle; FLIGHT—the Flight Director, the person in charge of the flight; CAPCOM, an astronaut who is normally the only controller to talk to the astronauts on board; and PDRS, responsible for robot arm operations.