Where should the head of the course arrow be to preclude an intercept angle of greater than 90 degrees?

To ensure that the intercept angle does not exceed 90 degrees, the head of the course arrow should be positioned in the top half of the Horizontal Situation Indicator (HSI). When the course arrow is oriented this way, it indicates that the aircraft is approaching the desired flight path from a relatively favorable angle, allowing for a smoother and more efficient interception.

Intercepting from the top half of the HSI means that the aircraft is on a converging path towards the desired course. This setup minimizes the necessary turn to join the airway or course, ensuring that the angle remains unobstructed and does not exceed the 90-degree threshold. As a result, the aircraft can align itself with the course without needing to make significant adjustments, thereby enhancing safety and precision in navigation.

In contrast, positions like the bottom half or edges of the HSI may result in a more acute or obtuse intercept angle, which could complicate the turn and lead to an interception that exceeds 90 degrees. Therefore, placing the head of the course arrow in the top half of the HSI is critical for maintaining an accurate and efficient flight path adjustment.