What initiates search and rescue procedures regarding an unclosed flight plan?

Search and rescue procedures are typically initiated when an aircraft does not cancel its flight plan within a specific timeframe after the expected arrival. In this context, if a pilot has a flight plan filed and fails to cancel it within 30 minutes of the anticipated landing time, it raises concerns for safety. This situation alerts authorities that the aircraft may be experiencing trouble, prompting them to take necessary actions to locate the aircraft and ensure the safety of those onboard.

The other options do not directly relate to the initiation of search and rescue procedures. While failing to fly above a certain altitude or not using correct frequencies may indicate various operational issues, they do not specifically trigger search and rescue protocols. Likewise, failing to submit a flight review pertains more to the pilot's compliance with certification requirements rather than the safety of a specific flight, and therefore does not contribute to the immediate concerns that would lead to launching a search and rescue operation.