What is the MSA predicated on?

The MSA, or Minimum Safe Altitude, is predicated on the requirements that ensure aircraft safety in relation to navigational guidance. In this context, being "plate dependent" refers to the MSA being designed based on specific instrument approach procedures illustrated on the approach plates. These plates outline all necessary safety altitudes that a pilot must adhere to while navigating to an airport during instrument flight conditions.

When a pilot is flying under instrument flight rules (IFR), they refer to these approach plates to understand the geometry and requirements of the approach. The MSA is calculated to ensure that the aircraft remains above the highest terrain or obstacle within a defined area around the airport, thus providing a buffer of safety. This is crucial for ensuring that the aircraft can clear any potential hazards while conducting an approach, particularly in low visibility or when flying at lower altitudes.

Other options, such as being terrain, weather, or time dependent, do not encapsulate the comprehensive approach found in the plate design. The MSA is specifically calculated and provided on these approach plates, which makes it inherently tied to the procedures outlined on them. This emphasizes the vital role that the approach plates play in ensuring safe aircraft operation in various conditions.