While arcing north on the 15 DME arc, what is your lead point to intercept the 310° radial outbound at 0.50 Mach?

When intercepting a radial while arcing around a distance measuring equipment (DME) arc, it is crucial to ensure a smooth transition from the arc to the desired radial. The lead point is the point at which you will begin your turn to intercept the radial, and it is influenced by factors such as your airspeed and the turn rate.

At 0.50 Mach, the indicated airspeed is relatively high, which means that the aircraft's ground speed is also significant. A ground speed of approximately 300 knots at sea level translates to a quicker approach to the intended radial. The general rule of thumb for determining the lead point in nautical miles when performing a turn to intercept a radial is to consider the Mach speed and the accompanying distance from the radial.

In this scenario, a lead of 3 nautical miles before the point of interception is appropriate, as it accounts for the transition time required to turn from the arc to the radial. This approach allows you to maintain proper airspeed while making a smooth and controlled transition, ultimately ensuring effective navigation.

Choosing a 3 NM lead point also reflects practical experience and standard procedures used in aviation to create a buffer for the turn and mitigate over- or under-turning issues, ensuring you align correctly with