Final answer:
The FAA mandates that an aircraft must stay five miles horizontally or 2,000 feet vertically (1,000 feet if under 29,000 feet in altitude) away from another aircraft for safety.
Step-by-step explanation:
In flight, Federal Aviation Administration (FAA) regulations require that an aircraft must maintain a safe distance from other aircraft. In flight, you should not transmit on mission radar within five miles horizontally or 2,000 feet vertically from another aircraft. If the altitude is less than 29,000 feet, the vertical distance reduces to 1,000 feet.
This includes a horizontal separation of five miles from another plane flying at the same altitude. Vertically, an aircraft must maintain a separation of 2,000 feet from another aircraft, but this is reduced to 1,000 feet if flying at altitudes less than 29,000 feet. These safety measures are put in place to prevent collisions and ensure the orderly flow of air traffic.