The Pressure Altitude and Cabin Pressure instruments show pressure altitude as derived by a barometric pressure sensor. If the sensor is in your iPad or iPhone, only Cabin Pressure will display a value.
If connected to a Sentry or other external device with a built-in barometric pressure sensor, both instruments will show the same value and Pressure Altitude will have an “Uncorrected” label.
If connecting to a Garmin device, there are settings available to specify what pressure is being sent from your Garmin device to ForeFlight.
Note: The available settings are dynamic and will be based on the connected devices. Some pilots may only have the option to choose "Use as Pressure Altitude" or "Use as Cabin Pressure Altitude".
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The "Pressurized Cabin" setting should only be enabled when the pressure sensor is installed in a pressurized cabin. If you fly a pressurized aircraft but the source of pressure altitude is from your pitot static system (GTX-345, Flight Stream 510), the "Pressurized Cabin" setting should be disabled.
If connected to a source that can transmit indicated altitude data to ForeFlight, the Pressure Altitude instrument will display a your indicated altitude with a “Corrected” label.
Note: If you are using a SatCom Direct router, you will need a Performance Plus or Business Performance subscription in order to see pressure altitude.