Traffic Collision Avoidance System (TCAS) helps pilots prevent disaster

An air traffic controller in Hawaii is being blamed for the near collision of two passenger jets that occurred on April 25, just after 11 p.m.

A United Airlines flight from Kona to Los Angeles was in the air for about a half-hour when it was forced to drop 600 feet.

The pilot told passengers that a U.S. Airways flight was heading toward them at the same altitude.

A national news report said the planes came within 2.2 miles of each other, caused by a miscommunication at Honolulu’s air traffic control tower.

Investigators with the National Transportation Safety Board and Federal Aviation Administration arrived in Honolulu Friday to investigate.

According to the FAA, a device known as a Traffic Collision Avoidance System, or TCAS, alerted the pilots, preventing a major disaster and saving hundreds of lives.

Avionics expert Will Gossley has been installing TCAs for 30 years.

“If you get within a certain distance, it will turn yellow, and if it gets close, it will turn red. So yellow is a warning and red is a danger,” he explained. “It’ll say traffic, traffic, traffic, and if you get too close, it’ll say pull up, pull up, pull up, or tell you to dive or whatever. Some of the systems have different callouts and the pilots are trained on what to do in that situation.

“It warns you fairly quickly, plus you have the visual. It comes across their flight displays,” he added.

The United Airlines flight was cruising at an altitude of 30,000 feet when it was forced to drop. One passenger described the incident as a violent and scary experience.

State Adjutant General Maj. Gen. Darryll Wong was in the cockpit of the last Aloha Airlines flight that arrived at Honolulu International Airport on March 31, 2008.

Wong said he started flying more than 33 years ago, in the days before technology like TCAS existed. Back then, he relied on others, and his own eyes and experience, to avoid mishaps in the air.

“Most pilots when they’re flying you rely on air traffic controllers to tell you where other airplanes are,” he said. “Plus, as a pilot, you should be very aware of where you are in the air traffic control system — if you’re close to the airport, father away, where the traffic can be from — and you’re constantly with your eyes out, looking at the skies to see if other airplanes are there.”

Gossley said there are a lot more planes in the skies nowadays, so the TCAS system has become that much more valuable for pilots.

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