Which is a disadvantage of passive sonar?

• A. Bearing error on target
• B. Perfect bearing solution
• C. Immediate and accurate TMA
• D. No data required

Answer: (A)

Passive sonar provides direction to a sound source without emitting anything, but it does not give you the distance to the source. The key drawback is bearing error on the target. The angle of arrival you derive from a hydrophone array is limited by array size, wavelength, environmental noise, multipath, and target motion. This means the bearing you estimate can be off by several degrees in realistic conditions, and that error translates into a significant cross‑range position uncertainty at operational ranges.

Since you don’t get range from a single passive observation, you can’t pin down an exact target location immediately; you have to accumulate multiple bearings over time and perform a track-while-search or TMA process. That process is inherently uncertain and not immediate or perfectly accurate due to the missing direct range information and the bearing inaccuracies.

The other options imply perfect bearing, immediate perfect TMA, or no data at all, which do not reflect how passive sonar actually performs; bearing error is the fundamental limitation.