Final answer:
The nominal operating range of AIS at sea is 20 nautical miles but can extend beyond 40 nautical miles under ideal conditions.
Step-by-step explanation:
The typical operating range of automatic identification systems (AIS) at sea is nominally 20 nautical miles. Automatic identification systems are used for tracking vessels and navigational aids which can be vital for collision avoidance and maritime security. However, the range can be affected by factors such as antenna height, signal strength, and atmospheric conditions. While AIS equipment is designed to meet a nominal range of 20 nautical miles, in practice, vessels with higher antennas and clear conditions can often detect signals from much further away, sometimes even beyond 40 nautical miles.