What to know about collision avoidance systems

Years ago, Mr Cox said, he went down to a Boeing 737 over Orlando International Airport, when the system warned him and his co-possession in traffic nearby. The pilots looked at another aircraft, but they saw nothing. The TCas then provided an urgent order: “Post”. Mr Cox said they did it and later saw a smaller aircraft beneath them. A conflict would be devastating, he said.

After a series of collisions, culminating in the 1986 crash of a passenger jet and smaller aircraft near Cerritos, California, who killed 82 people, Congress entrusted the federal aviation administration to demand TCA on all major commercial planes. However, it is optional on military aircraft and it is not clear whether the army helicopter involved in the crash on Wednesday was equipped with it.

This crash happened at a relatively low altitude, however, where the most critical TCAS conflict instructions would be limited by the design, Mr Cox and other security experts said. As jet aircraft approach an airport, they are likely to be closer to each other than at higher altitudes. As a result, the system restricts the notifications it issues to avoid the challenge and obstruction of security.

Automatically dependent monitoring

In recent years, FAA has required all passenger airlines and many other aircraft to use another system, called automatic dependent surveillance. Technology transmits the location, altitude, speed and other data of the aircraft installed every second. These emissions can be received from other aircraft or equipment in the ground.

Air traffic controllers and many passenger pilots are based on information obtained from ADS-B systems that use devices that can provide detailed aircraft maps in one area. This information is useful for visualizing what is happening in the air, but the system usually does not issue the type of notifications made by TCAS. Still, ADS-B is useful for pilots, especially when flying in bad weather or occasionally when visibility is low, said Dr. Hassan Shahidi, president of the non-profit flight security institution.