(LOS ANGELES) -- Kevin Townsend was returning home to California from a trip to Hawaii last month, flying high above the Pacific Ocean, when his plane suddenly dropped hundreds of feet.
"It was like being in freefall," Townsend said, recalling the experience.
The trip took place on April 25, and Townsend spent the next few weeks trying to determine what happened that caused his commercial passenger flight from Hawaii to have to suddenly maneuver in mid-air.
He found out from the flight crew, the airline and the Federal Aviation Administration that his plane, a United Airlines Boeing 757, had come within 20 seconds of a potential collision with another commercial flight in the same flight path.
United Airlines told ABC News they are reviewing the incident with the National Transportation Safety Board. American Airlines, which merged with US Airways, issues a statement on behalf of its sister airline: "The safety of our passengers and crew is our top priority. We are working with the authorities as they look into what may have happened."
"I was flying from Kona on the western side of Big Island and connecting through LAX to go home to San Francisco. We climbed up, looped around the Big Island, and reached cruising altitude, and stayed there for 5 or 10 or even 15 minutes," Townsend told ABC News on Thursday.
"All of a sudden out of nowhere, the plane cuts into a steep dive," he said.
"It was like being on an elevator dropping really quickly. You start to fall with gravity, not like in a fighter jet pressed up against your seat. It was like being in freefall. It was kind of exhilarating, like you’re weightless," he said.
The sensation lasted five or six seconds, he said, during which a few passengers around him began screaming. His mind raced through the possibilities of what could be happening.
"It was so sudden that it seemed like something had gone wrong, because you don’t expect that at all. But there was no sound involved and the plane didn’t seem to be out of control. It was tough to conceive of why it happened. Your body thinks, 'did the engines just go out and we’re diving into the ocean?' But then you feel like this is somewhat controlled," he explained.
The FAA's Pacific Division issued a statement saying the FAA and NTSB are investigating the April 25 incident.
The United Boeing 757 responded to an alert to avoid a US Airways Boeing 757 about 200 miles northeast of Kona, the agency said.
"A joint FAA-NTSB investigation team will arrive at the Honolulu Control Facility today. The FAA began investigating the incident immediately and has taken steps to prevent a recurrence," the statement said.
Townsend wrote about his experiences on the website Medium, where he gave a detailed account of what he found out while investigating flight safety regulations.
He said that a little while after the incident, the flight attendant came on the plane's loudspeaker and made a joke, saying, "Well that was unexpected," and reminding passengers why it's important to wear seatbelts when the seatbelt light is on.
"Ironically the seatbelt light was off when it happened," Townsend said. The flight attendant also announced that all the passengers would be receiving free Direct TV for the rest of the light.
"It seemed like [the flight crew] was really shaken up by it, and that made me want to find out more about what had happened," he said.
He spoke to the United flight crew at the gate in Los Angeles and they told him the plane had made the maneuver to avoid another aircraft in its flight path, a US Airways flight.
"They were really candid," he said.
After he got home safely, Townsend began calling the airlines and the FAA to find out how it was possible that two planes could come so close to crashing.
He said that the companies and agencies were forthright and spent more than an hour on the phone with him talking about the close call, explaining how rare it is, and going over the ways that data is collected to avoid future incidents.
"I gained an understanding of how traffic collision avoidance works," he said, though he came away from the conversations believing that the regulatory agencies could do a better job of collecting data and analyzing it to prevent future incidents.
Townsend said he is still comfortable with the idea of flying though has his concerns.
"I think I have a keener awareness of what flying means. I think you have to accept there are risks to it," he said.
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