911 Plane
In the term "911 plane," the word "plane" is a noun, serving as the core subject. The numeral "911" functions as an attributive noun (also known as a noun adjunct), which acts like an adjective to modify "plane." Therefore, the entire phrase operates as a compound noun or noun phrase, with "plane" being the main point, specifically identified and contextualized by "911." An attributive noun is a noun that modifies another noun that follows it, specifying its type, origin, or context. In this case, "911" is not a quantifier or a simple descriptor; it is a proper noun representing the specific historical events of September 11, 2001. Its function is to distinguish these specific aircraft from all others. The grammatical structure pinpoints the subject not as the event itself (9/11), but as the physical objects (the planes) directly involved in that event. ...