Final answer:
Commercial airliners are able to fly without running into each other due to careful regulations by the Federal Aviation Administration, which mandate specific distance requirements between aircraft at the same altitude. These regulations provide sufficient separation to prevent collisions.
Step-by-step explanation:
Commercial airliners are able to fly without running into each other because their flight paths are carefully regulated by the Federal Aviation Administration. According to regulations, each airplane must maintain a distance of five miles from another plane flying at the same altitude. Additionally, planes must also be 2,000 feet above and below another aircraft, with the altitude requirement reduced to 1,000 feet if the altitude is less than 29,000 feet. These regulations ensure that planes have sufficient separation to avoid collisions.