What does a NOTAM D indicate?

A NOTAM D, or a Notice to Air Missions (formerly known as Notice to Airmen), indicates a significant change to the airport or airspace. This type of NOTAM includes information on changes that could impact flight operations, such as changes in use of a runway, availability of an airport, or alterations in navigational aids. Since pilots rely heavily on timely and accurate information to assess their flight environment, NOTAM D serves as an important alert for potential issues they may encounter.

While not all NOTAMs are significant, those categorized as NOTAM D are specifically meant to inform pilots about substantial operational changes that require awareness before takeoff and during flight. Understanding the implications of NOTAM D is crucial for safety and compliance with aviation regulations, which is why it indicates a more serious update compared to regular NOTAMs or those that deal with minor updates or specific conditions.