What does an "inoperative" indicator on an aircraft signify?

An "inoperative" indicator on an aircraft signifies that an instrument or system is malfunctioning. When an indicator shows that it is inoperative, it alerts pilots and maintenance personnel that the specific instrument or system is not working as intended. This is crucial for the safe operation of the aircraft, as it can affect flight performance, navigation, communication, or safety systems. Understanding the meaning of these indicators allows pilots to take appropriate actions, such as conducting checks, reporting the issue, or implementing alternative procedures.

The other options imply different meanings that do not directly align with the term "inoperative." For example, a low fuel indicator would typically illuminate or indicate a specific fuel quantity, not an inoperative state. A functioning aircraft would not show any inoperative indicators, and suggesting that an inoperative indicator means the aircraft is grounded conveys a misunderstanding of how indicators operate; they are designed to inform pilots of issues rather than dictate flight status directly.