B737NG - PRESURIZATION

B737NG Pressurization Panel located on the right fwd side of FWD OVERHEAD panel.

Setting Cruise Altitude. and landing airport altitude.

Pressurization system can be selected with 3 position.

the switch located bottom on the picture. AUTO, ALTN, MAN

AUTO mode - 2 CPC(Cabin pressurization computer) will control pressurization system

ALTN mode - one of the CPC will control pressurization system

MAN mode - manually controled by pilot. by opening or closing the Main outflow valve

Controlling switch located below the Main outflow valve Gauge.

*when MAN mode selected, control outflow valve just clicking in short time so that cabin climb rate shouldn't go over 500fpm.

otherwise, passengers eardrum would be affected by high rate of change

*AUTO FAIL light illuminated -

(both)2 CPC have failed.

Excessive differential pressure (8.75psic)

Excessive cabin pressure change (+-2000)

High Cabin Altitude (above 15,800ft)

*AUTO FAIL and ALTN lights illuminated - one of the CPC has failed, and the other CPC is taking over

*OFF SCHED DESCENT illuminated - Descent before reaching cruising altitude which is set on the Pressurization panel

*when OFF SCHED DESCENT illuminated, 

 if you turning back to the airport you've takeoff - no action required.(CPC memorizes takeoff altitude and doing his work)

*ALTN light illuminated - knob switched ALTN mode and one of the CPC will take control. 

*MANUAL light illuminated - knob switched MAN mode and Pressurization controlled by pilot.

*ALT HORN sounds over 10,000ft of cabin pressure.

 pushing ALT HORN CUTOUT will inhibit this sound.

*Large needle on the gauge means Cabin differential pressure(PSID)

*Small needle on the gauge means Cabin pressure altitude

*Appropriate chart for cabin altitude related to the flight altitude is located as well