(Loss of all generators in flight could also put you in this position - with no AC power the Automatic mode is unavailable.
TENSR 800 MANUAL MANUAL
But there has to be a way to manually control the pressurization, so the Manual mode is it.
TENSR 800 MANUAL SIMULATOR
Controlling the pressurization manually takes a lot of time & attention by the First Officer, so it isn't something that's practiced in the aircraft, and because the really big cues that you're doing it well or poorly come from what your ears feel, it isn't something that's done in the simulator either. Getting to this point is quite rare, but it can happen.
(The automatic modes need AC power to operate.)įinally, if both digital controllers fail in flight, then the crew needs a way to control the pressurization, and the manual mode is used for this. Third, if the flight must be conducted unpressurized, the manual mode allows this - open the outflow valve fully, and there is no pressure differential - say if you had a damaged window that needs to not be pressurized while the aircraft is ferried to where the window can be replaced.įourth, in the case of an emergency evacuation, it may be necessary to quickly depressurize the aircraft, and the manual mode allows the crew to open the outflow valve with only DC (i.e. This used to be a check performed by the pilots, but (in large part due to the Helios accident mentioned), it is now a maintenance-only function for many operators.
Second, the manual mode is used to verify that the outflow valve DOES open and close. It isn't common, but there are some checks that require it. First, if you need to perform a ground pressurization check, the pilot or mechanic uses the manual mode to close the outflow valve and allow the aircraft to pressurize on the ground. There are several reasons that this control is sometimes desirable none of them are particularly common. With both the digital and the analog controllers, the Manual mode gives the pilots direct control over the outflow valve.
The ALTN mode makes the "other" controller primary, so that if the primary controller fails, the other one can be selected. In the digital panel, the Auto mode selects between two digital controllers which swap every flight so that if #1 is primary (in control in the Auto mode) this flight, #2 will be primary next flight. Older 737's may use this digital controller or an analog controller with Auto, Standby, Manual AC and Manual DC modes.įrom, which also has a depiction of the older, analog panel. The B737 Next Generation models (737-600, -700, -800, and -900) all use a digital cabin pressure controller, which has AUTO, ALTN, and Manual modes.
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