How is the decision made regarding the Minimum Altitude Point (MAP) during a non-precision approach without a DME?

The Minimum Altitude Point (MAP) during a non-precision approach without a Distance Measuring Equipment (DME) is determined using a timing method chart found on the approach plate. This approach relies on timing segments after a defined point, such as the final approach fix, and involves the pilot calculating when to reach the MAP based on the elapsed time from that point along the approach path.

This timing method is essential because, during a non-precision approach, where lateral navigation is often performed without precise distance information (as DME would provide), pilots must rely on time as a proxy to ensure they do not descend below the minimum altitude before reaching the MAP. The approach plates generally include information regarding the expected time for segments, which helps pilots make accurate decisions on when it is appropriate to proceed to the MAP.

Using visual inspection of landmarks or following GPS indications would not be as reliable, as they can be subjective or dependent on external factors like visibility conditions. Relying solely on aircraft instruments would also lack the practical timing references provided in the approach plates, making them less effective for this specific decision-making process.