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I pilot the plane cessna in the simulator for a long time, and I always saw this VAC indication next to the Ammeter. What is VAC for and how to read it?

instrument

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    $\begingroup$ Air pressure? I don't know dude. $\endgroup$ Mar 10 '20 at 13:37
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In short, it is the vacuum gauge. It measures the vacuum pressure in Inches of Mercury. It runs/powers your non-electrical gyroscopic instruments. Those are your Attitude Indicator, your Directional Gyroscope, and sometimes your Turn Coordinator. These are all necessary to fly by Instrument Flight Rules.

Read these:

PHAK

Airplane Flying Handbook

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  • $\begingroup$ That is, it is the basis for all instruments that use air pressure to work. But how to read this instrument? For example, if the indication is 4 or 6, what does it mean? $\endgroup$ Mar 10 '20 at 13:41
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    $\begingroup$ @JeanExtreme002 it means 4 or 6 "Inches of Murcury" - which is a/the unit of measurement for "pressure". The guage would indicate 4.5-5.5 is the correct range (based on the green arc) $\endgroup$
    – Jamiec
    Mar 10 '20 at 13:43
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    $\begingroup$ @JeanExtreme002 - In general, your engine gauges will have an operating range indicated by colored markings on the gauge. This is to facilitate rapid acquisition of the required data. If the gauge is in the green, you are good. If it is not in the green, things are going to get rather sporty quickly. The above indication pictured would indicate that you have little to no vacuum pressure. Therefore, your Attitude Indicator and Directional Gyro will not work. $\endgroup$
    – Dean F.
    Mar 10 '20 at 13:54
  • $\begingroup$ Is the "suction" indicator on some planes the same as the VAC? $\endgroup$ Mar 10 '20 at 13:59
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    $\begingroup$ It would behoove you to read the FAA manuals I have attached. They explain many of the questions you may have. If something is unclear after reading these, come back and ask questions regarding that specific section of the books. It will make your simming more effective and make more sense. $\endgroup$
    – Dean F.
    Mar 10 '20 at 14:17

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