Final answer:
The difference between EVLOS and BVLOS is that in EVLOS operations, visual observers are used to extend the line of sight, while in BVLOS operations, advanced technologies are employed to operate the UAS beyond the visual line of sight of the pilot or observers. The correct response is B.
Step-by-step explanation:
The difference between Extended Visual Line of Sight (EVLOS) and Beyond Visual Line of Sight (BVLOS) operations pertains to how unmanned aircraft systems (UAS) are managed visually during flight. In EVLOS operations, the pilot or remote operator maintains indirect visual contact with the UAS through a series of visual observers who are positioned in such a way that at least one of them can always see the aircraft. This 'daisy-chain' approach extends the visual range while still ensuring that the UAS is monitored by human eyes. On the other hand, BVLOS operations allow the UAS to operate beyond the direct visual line of sight of the pilot or visual observers. This is made possible through advanced technologies that can include radar, onboard sensors and cameras to provide the necessary situational awareness for safe operation.
Selecting the correct response, the answer is B: EVLOS operations enable the crew to daisy-chain visual observers, while BVLOS operations rely on advanced technologies to sense and avoid. Option C and D are incorrect as the requirement for training is not what primarily distinguishes EVLOS from BVLOS. Additionally, Option A is incorrect as there is a significant operational difference between the two terms and they are not used interchangeably.