When an instrument face displays a flag, what does this typically indicate?

When an instrument face displays a flag, what does this typically indicate?

• A. The instrument has failed or is unreliable
• B. The instrument is calibrating
• C. The instrument is overrange
• D. The instrument is in standby

Answer: (A)

A flag on an instrument face is a warning that the data shown is invalid or unreliable. It usually appears when the sensor, processor, or data path has failed or lost integrity, so the system suppresses the normal reading to prevent pilots from acting on a faulty value. When you see it, treat that instrument as failed and cross-check with other indicators or switch to the standby instrument and follow the applicable failure procedures. Flags do not indicate calibration in progress, and they are different from what you’d see if the display were simply overrange or in standby mode, which are shown with other indicators. The presence of the flag is therefore a sign of a failed or unreliable instrument.

A flag on an instrument face is a warning that the data shown is invalid or unreliable. It usually appears when the sensor, processor, or data path has failed or lost integrity, so the system suppresses the normal reading to prevent pilots from acting on a faulty value. When you see it, treat that instrument as failed and cross-check with other indicators or switch to the standby instrument and follow the applicable failure procedures. Flags do not indicate calibration in progress, and they are different from what you’d see if the display were simply overrange or in standby mode, which are shown with other indicators. The presence of the flag is therefore a sign of a failed or unreliable instrument.