Why is the Inertial Navigation System (INS) critical for military aircraft?

The Inertial Navigation System (INS) is critical for military aircraft because it operates independently of external signals, such as GPS. This autonomy is particularly important in military operations where reliance on external navigation aids could make aircraft vulnerable to jamming or other forms of interference. The INS uses a combination of accelerometers and gyroscopes to track the position, orientation, and velocity of the aircraft, allowing it to navigate accurately even in environments where GPS signals may be unreliable or unavailable.

In military scenarios, the ability to maintain accurate navigation without depending on ground-based or satellite systems enhances mission effectiveness and operational security. The INS ensures that aircraft can function in diverse and hostile conditions, thereby contributing to successful mission execution. This capability for self-contained navigation is why option A is the correct answer.