In which scenario would the use of a lost link contingency flight plan be crucial?

The use of a lost link contingency flight plan becomes crucial in the scenario where the UAS loses communication with the operator. This situation can occur due to various reasons such as signal interference, equipment failure, or exceeding operational range, which can leave the UAS without control.

Having a well-defined lost link contingency flight plan is essential because it ensures that the UAS can respond appropriately to maintain safety and minimize risk. Such plans typically outline pre-programmed responses, like returning to a specified home location or executing a controlled descent, thus helping to mitigate potential collisions, crashes, or other hazards that could arise when communication is lost.

In contrast, scenarios like takeoff or performing pre-flight checks are critical phases of flight where communication is typically maintained and does not necessitate contingency plans for lost link situations. When signal strength is strong, there is less risk of losing communication, so a contingency plan focused on lost link scenarios is not as critical.