What is the maximum vertical height of the ADIZ?

The maximum vertical height of the Air Defense Identification Zone (ADIZ) is up to and including Flight Level 600 (FL 600). This designation means that the ADIZ extends from the surface of the Earth up through various altitudes and can reach very high flight levels, specifically up to 60,000 feet. The purpose of establishing the ADIZ at this altitude is to ensure that all aircraft operating within this zone can be adequately identified and monitored by air traffic control and military defense systems, which is crucial for national security and safety.

When considering the other choices, they represent altitudes that are below the maximum limit of FL 600. Therefore, they do not encompass the full operational capacity and requirements of an ADIZ, which can potentially involve aircraft operations at much higher altitudes. The control and oversight of airspace at such altitudes is vital in order to maintain a secure airspace environment.