The story behind ending mid-air collisions

The first collision between airliners occurred in 1922 in France. The loss of both airplanes and all occupants proved the need for better air-traffic control. Following the accident investigation, recommendations for airways (highways in the sky) and onboard radios were made. Air-traffic control was born.

As airliners grew and improved, the demand for better air-traffic control grew. Larger cities became more crowded as increasing number of airplanes flew in and out. Pilots reported their positions regularly via the radio to let others know where they were and their estimated time over the next required reporting point, but collisions still occurred.

In the 1930s, ’40s and early ’50s, there were 13 accidents involving collision of airliners. Improvements were being made, but the collision of TWA Flight 2 and United Flight 718 on June 30, 1956, causing 128 fatalities, was the catalyst for change in aviation. For the first time, more than 100 people had perished in an aviation accident. The United DC-7 and TWA Constellation collided at 21,000 feet above the Grand Canyon. A memorial of this tragedy remains at the spot of the collision.

Investigators found that the TWA pilots were flying visually after receiving clearance from the air-traffic controller. They were maneuvering around clouds and did not see the United flight. Both flights were off the airway on which they were told to fly. An outcry from the public and politicians quickly arose.

As a result of the Grand Canyon accident and others, in 1958 the Federal Aviation Administration was formed and made responsible for all airspace in the United States. Upgraded air-traffic control facilities were built, allowing for positive control of airliners in the airspace. The number of collisions decreased, but occasionally an airliner still collided with another airplane.

While the FAA was improving air-traffic control, scientists were looking for a technology that could help pilots avoid the risk of collision. By the late 1970s, the push was producing results. A new system known as the Traffic Collision Avoidance System (TCAS) was maturing and ready for testing. With TCAS, if there is a potential collision developing, the system alerts the pilots and provides climb and descend instructions. In 1981, Piedmont Airlines flew the first operational TCAS on a regularly scheduled flight. Two Piedmont Boeing 727s flew with specially trained observers to validate the system. It worked.

Airlines and manufacturers worked with the FAA to improve TCAS and implementation began, but, sadly, not quickly enough to avoid a midair collision near Los Angeles in 1986. An AeroMexico DC-9 struck a private airplane as it descended to land at LAX. All aboard both airplanes perished. The need for TCAS was clear.

The FAA recognized the safety improvement offered by TCAS, mandating it for all airliners with more than 30 seats in 1993. Since TCAS become standard equipment in airliners, the risk of mid-air collision has dropped dramatically.

Aviation safety depends on people, organizations and technology. Working together and utilizing the technology is the story of how the number of mid-air collisions has fallen to near zero. www.wwltv.com