NTSB NTSB

Damage done to the Hoboken Terminal in New Jersey after a commuter train crash in September 2016. Federal investigators attribute this accident and one in New York to engineers' untreated sleep apnea. Chris O'Neil/AP hide caption

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Chris O'Neil/AP

A photo provided by the Indiana State Police shows the wreckage from a small plane crash Saturday night in southeastern Indiana. An executive at the NTSB was among the three people killed when the Cessna crashed into the woods. Indiana State Police/AP hide caption

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Indiana State Police/AP

An NTSB investigation on a deadly hot air balloon crash in July 2016 found that the pilot had a "pattern of poor decision-making" and was impaired by drugs and medical conditions. Here, authorities block a road near the crash site in Maxwell, Texas. Aaron M. Sprecher/AFP/Getty Images hide caption

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Aaron M. Sprecher/AFP/Getty Images

A Metro-North passenger train rolls through the Spuyten Duyvil station in New York in December of 2013, days after a train derailed in a deadly crash as it approached the station. Craig Ruttle/AP hide caption

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Craig Ruttle/AP

Emergency crews work on the scene where a train hit a charter bus in Biloxi, Miss., Tuesday. The National Transportation Safety Board says the freight train was traveling about 19 mph at the time of the crash. Gerald Herbert/AP hide caption

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Gerald Herbert/AP

One person was killed and more than 100 injured when a New Jersey Transit train crashed into the platform at Hoboken Terminal on Sept. 29. Investigators say they have found no defect in the brakes. Eduardo Munoz Alvarez/Getty Images hide caption

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Eduardo Munoz Alvarez/Getty Images

Authorities investigate the site of a hot air balloon accident in Maxwell, Texas, on Saturday. All 16 people aboard the hot air balloon died after it hit tall, high-voltage power lines. Aaron M. Sprecher/AFP/Getty Images hide caption

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Aaron M. Sprecher/AFP/Getty Images

Emergency workers search for injured passengers after an Amtrak train carrying more than 230 people from Washington, D.C., to New York derailed in Philadelphia in May 2015. Mark Makela/Getty Images hide caption

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Mark Makela/Getty Images

Investigators onboard the USNS Apache retrieved the tow pinger that was used to look for El Faro's voyage data recorder on Oct. 24. Although the wreckage of the ship has been found, the recorder is still missing. John Paul Kotara II/AP hide caption

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John Paul Kotara II/AP

National Transportation Safety Board Chairman Deborah Hersman briefing reporters about the July 2013 crash of Asiana Airlines Flight 214 in San Francisco. Justin Sullivan/Getty Images hide caption

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Justin Sullivan/Getty Images