PHILADELPHIA — The union for Amtrak’s locomotive engineers urged the railroad on Tuesday to put a second crew member at the controls of trains on the busy Northeast Corridor, where a derailment killed eight people and injured more than 200 others.

“The public would never accept an airline operation with a single person in the cockpit,” the Brotherhood of Locomotive Engineers and Trainmen said in a statement. “There is no reason that rail employees and rail passengers’ lives should be viewed any differently.”

Brandon Bostian, 32, was alone in the locomotive of Train 188 when it derailed May 12, about 10 minutes after departing Philadelphia for New York.

Amtrak hasn’t had a second crew member in the locomotive of its Northeast Corridor trains since Congress ended the requirement in the early 1980s, the union said.

Amtrak didn’t immediately comment on the union’s request.

The National Transportation Safety Board is looking into why the train was going more than double the 50 mph limit around a sharp curve. It is also investigating whether an object may have struck the locomotive’s windshield before the crash.

The FBI said it found no evidence a grapefruit-sized fracture on the windshield was caused by a firearm, and the NTSB said it was unsure anything had struck the vehicle.

Investigators said Bostian, who was among the injured, told them in an interview that he couldn’t recall anything from the last 3 miles before the derailment.

About 20 people remained hospitalized Tuesday. Five were listed in critical condition.

Authorities say it could be a year before they determine the probable cause of the derailment.

Train 188 had a five-member crew — including a conductor who is still hospitalized with serious injuries and assistant conductors — but they were in the passenger coaches, closed off from the locomotive.

The union Tuesday called on Congress to require a second “fully trained and qualified” crew member in each locomotive, but stopped short of demanding that person also be an engineer.

It also blamed lawmakers for deep funding cuts it said translated into fewer Amtrak crew members and greater lag time in the implementation of technology that slows speeding trains.

“So long as those in Congress see fit to underfund the operation, they undermine their own mandate and shortchange the safety of the traveling public,” the union said.

The hospitalized conductor, Emilio Fonseca, has sued Amtrak, claiming the railroad was negligent and careless. His lawyer said Tuesday he suffered a broken neck, broken back and other serious injuries.

The attorney, Bruce Nagel, said Fonseca, 33, of Kearny, New Jersey, was in a bathroom in the first car of the train at the time of the derailment and that his location likely saved his life.

Fonseca managed to get out of the train and remembers telling people to watch out for electrical wires, Nagel said. Doctors have dubbed him the “miracle man” for surviving the crash.

“Obviously the hand of God was on his shoulder,” Nagel said.