Final answer:
Class E airspace is controlled airspace that extends from 1,200 ft AGL to below 18,000 ft MSL, which is not Class A, B, C, or D airspace. The FAA regulates commercial airline paths within this airspace, requiring specific horizontal and vertical separation standards akin to the positional restrictions found in quantum mechanics.
Step-by-step explanation:
The airspace that is generally classified as controlled airspace that is not Class A, Class B, Class C, and Class D is Class E airspace. This type of airspace extends upward from 1,200 feet Above Ground Level (AGL) to, but not including, 18,000 feet Mean Sea Level (MSL). The Federal Aviation Administration regulates the flight paths of commercial airliners within this airspace to ensure safety and prevent collisions. Commercial airlines must maintain specific separation standards, such as a horizontal distance of five miles from another plane at the same altitude, and a vertical separation of 2,000 feet above or below another aircraft when over 29,000 feet, or 1,000 feet if below this altitude.
Similar to how quantum mechanics restricts the locations of electrons, commercial aircraft are limited to certain positions during flight. These regulations are enforced through a system of air traffic control, where each aircraft's position and altitude are monitored and controlled. The precise coordination and flight regulations allow for the safe operation of many aircraft in the sky at once without the risk of collision.