787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Air Systems -
Pressurization System
Description
Copyright © The Boeing Company. See title page for details.
2.30.2 D615Z003-TBC
During descent, cabin altitude decreases to slightly below the FMC planned
landing altitude. This ensures that the airplane lands pressurized. Landing altitude
barometric pressure correction comes from the captain’s altimeter setting.
At touchdown, both outflow valves open to depressurize the cabin.
For high altitude takeoffs, if the takeoff field elevation is higher than 8,000 feet,
the cabin descends to the target altitude while the airplane is climbing.
For high altitude landings, if the destination airport elevation is greater than 8,000
feet, the cabin altitude climbs to 6,000 feet after takeoff and remains there during
cruise. The cabin altitude then starts climbing to the destination airport elevation
when appropriate.
Pressurization System Manual Operation
The pressurization system is in the manual mode when the OUTFLOW VALVE
switches are set to MAN.
The system is manually operated by:
• setting the OUTFLOW VALVE switches to MAN
• holding the related OUTFLOW VALVE MANUAL switch to OPEN or
CLOSE
Outflow valve position is displayed on the EICAS display. If the outflow valve
position is not available on EICAS, holding the respective OUTFLOW VALVE
MANUAL switch in the desired position for 30 seconds moves the valve from full
open or closed to the selected position.
Landing altitude (normally provided by the FMC) can be manually set using the
LANDING ALTITUDE selector. Landing field selection limits are 2,000 feet
below sea level (-2,000) to 14,000 feet above sea level. Pulling the selector out to
the detent removes the FMC landing altitude and displays pressurization system
indications on the EICAS display. The knob is rotated clockwise to increase or
counterclockwise to decrease the landing altitude setting. Two rates of increase or
decrease, low and high, are available in each direction from the starting position.
Operation With Loss of Cabin Pressurization
With a sudden loss of cabin pressurization, the outflow valves close immediately
in an attempt to control the cabin pressure. After descent, when the airplane and
cabin altitudes are approximately equal, the outflow valves open to protect the
airplane against negative pressure differentials.
It is important that the flight crew not attempt to manually close the outflow valves
during the descent.
August 14, 2009
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