How does the line spacing for number 2 in echelon compare to that in route?

In the formation flying context, the line spacing for number 2 in echelon is specifically defined to help maintain visual reference and proper formation integrity. The answer that indicates it is 30 degrees aft of the lead aircraft's longitudinal axis (LAB) up to LAB highlights the critical aspect of formation flying where spacing is not only about distance but also about angular alignment.

When in echelon formation, number 2 maintains an angle relative to the lead aircraft rather than just maintaining a set distance. This angular reference allows for better visibility and reduces the risk of collision while still ensuring the formation stays cohesive. The designation of "30 degrees aft" emphasizes the importance of maintaining this specific angle to avoid losing sight of the lead and to facilitate smoother maneuvering.

In comparison, line spacing during route formation does not require maintaining this specific angular relationship—it's more about maintaining a consistent distance behind the lead without the emphasis on the angle. Thus, the nature of the answer underscores the importance of understanding the geometric relationships in formation flying and ensures that pilots can manage their positioning effectively to ensure safety and precision in maneuvers.