The release of the case docket indicates the fact-gathering phase of the investigation is complete. There will be analysis before the NTSB determines the probable cause of the Feb. 22, 2020, crash on Interstate 15 in north San Diego County.
The bus was on a run from Los Angeles to San Ysidro, a neighborhood just north of the U.S.-Mexico border, when it went off the highway on a slight curve in the Pala Mesa area and rolled down an embankment, ejecting several passengers.
The findings on the physical condition of the bus are contained in a report by an NTSB official in charge of the “vehicle factors” portion of the investigation.
The bus operated by Executive Lines Inc. had four rear wheels in dual configurations on each side.
A device that uses a laser to measure tire tread depth found the left outside tire was in a condition that required immediate replacement and the other three rear tires were “marginal.”
A telephone message seeking comment from Executive Lines in the Los Angeles suburb of El Monte was not immediately returned.
The report said inspections found no damage to steering system components.
The NTSB documents also showed that after the crash the bus driver underwent several standard sobriety tests at a California Highway Patrol station and voluntarily gave a blood sample that was screened for at least 150 types of drugs and the test results were negative.
The driver also underwent another test on Feb. 24, 2020, and the results again were negative, although the NTSB noted it was past the time limits set for alcohol and drugs.
The documents also show that the driver told investigators he got into the far right lane after it began to rain heavily and he felt the bus start to drift to the left while he was still steering straight.
The bus “wandered” into the adjacent two lanes, and he steered to the right in attempt to get to the far right lane, pull onto the shoulder and stop, he told the investigators.
The bus went off the road and tumbled, ending up on its roof.
“When asked what he thought caused the crash, the driver stated there was water coming down the slope, moving at a rapid rate. He believes it came out into the lane and caused the bus to hydroplane,” the human performance factors report said.
The driver had been working for a little over three hours after two days off, according to the reports.
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