Define "class E airspace."

Class E airspace is defined as controlled airspace that is not classified as Class A, B, C, or D. It typically begins at 1,200 feet above ground level, although it can also exist at lower altitudes in certain areas, such as near airports. This class of airspace allows for a mix of both IFR (Instrument Flight Rules) and VFR (Visual Flight Rules) operations. It is essential for pilots to understand Class E airspace because it helps delineate areas where different air traffic regulations apply, thus facilitating safe separation and efficient usage of airspace among various types of air traffic.

The remaining options describe airspace classifications incorrectly. Uncontrolled airspace, which begins at ground level, refers specifically to Class G airspace, while space above 24,000 feet is not restricted solely to military flights, as various civilian and commercial flights can operate in higher altitudes, assuming they are authorized under the applicable air traffic control regulations. Lastly, there is no classification of airspace that solely restricts access to international flights; airspace regulations typically apply to all flights regardless of their origin or destination. Understanding these distinctions helps maintain safety and order in aviation operations.