A BART commuter recounted to the agency’s governing board Thursday a nightmare scenario that left panicked passengers trapped in a smoke-filled train for several minutes, saying they were not told by the operator of what was going on.

Alan Mond, who has been a BART rider for over a decade, recounted what he said happened at 5:51 p.m. on Aug. 29 on his way home to the East Bay.

“When the train stopped under the tunnel, there was no explanation at all. I tried pressing the train operator call button. There was no reply,” Mond said.

“For five minutes, as the car filled with smoke, passengers were frantically trying to figure out what to do and how to exit the train, fearing for their lives,” he said, adding that passengers breathed smoke for 20 minutes before the train started again and ultimately reached West Oakland station.

“I urge the board to make immediate communication protocols a priority,” Mond said.

But a top BART official sought to assure the agency’s governing board that a review of in-cab video shows the operator alerted passengers about the smoke issue nine times over 17 minutes, “including encouraging patrons to stay calm and do not exit the train.”

It is not clear, however, what led passengers like Mond to say they did not hear any notifications.

Mond also asked why the train was ever allowed to enter the tube given there had been a report of a fire on the train ahead of it.

“Why was the 5:17 train even allowed to depart?” he said. “Why did operations not hold our train until the situation was understood?”

BART officials said the fire hit the first train just as it was leaving the tunnel on the East Bay side, and the following train Mond was on was just entering the Transbay Tube.

“It was already in the tube when the first incident train had sustained the damage,” said deputy general manager Michael Jones.

But experts noted that the tube is more than three miles long, giving BART plenty of time to stop the train behind, well short of where the smoke had filled the tunnel on the Oakland side.

Instead, BART officials told the board, the following train only stopped inside the tube when the operator saw smoke up ahead, blocking his view.

They suggested some smoke was allowed into a train car when a passenger tried to open the emergency door. But they also offered another reason: the operator may have allowed the ventilation system to continue to draw smoky air from the outside instead of simply shutting down the system.

While saying BART is still investigating what caused a fire on a train in front of the one Mond was riding, BART assistant general manager for operations Shane Edwards pointed to a photo of a “blown” heat insulator on the third rail inside the tunnel. Edwards said BART is still inspecting the entire tube as it determines what led to that insulator failure.

Meanwhile, Sylvia Lamb, assistant general manager for infrastructure, apologized and separately took blame for the network failure that occurred the morning of Sept. 5. She said failure occurred as BART engineers had just turned on a replacement switch on BART’s network at Montgomery station. What led to a “network storm” that overloaded the system is still being investigating, Lamb said.