A tour bus loaded with dozens of passengers barreled down one of San Francisco's steepest streets at the tail end of rush hour last Thursday evening after its brakes partially failed.
The City Sightseeing bus shot down California Street shortly before 7 p.m., but a bit of luck and quick reactions by the bus driver - who swerved into oncoming traffic to avert a crash - appear to have saved passengers from harm.
City Sightseeing general manager Andrew Smith said today it appears there was a problem with the bus' brakes.
"The brakes didn't fully come on," he said. "There was no actual total failure."
Smith declined to provide details because the investigation is still under way, but said, "As far as I can gather, the driver decided the safest thing to do was what he did."
All was quiet as the bus glided past Grace Cathedral at the top of California Street, said Kara Chanasyk, a 35-year-old San Francisco resident who was on the tour.
California Street was the most direct route, albeit the steepest, to the tour's final destination at the Embarcadero.
Most of the passengers were crammed into seats on the bus' open-air upper level on the clear, warm evening. Only two passengers - Chanasyk and her mother - were seated on the lower level with the driver, where the scenic turned terrifying.
Chanasyk noticed something awry when the driver laid on the horn as it passed through the intersection at Mason Street, where the green light gave them safe passage.
"We were accelerating tremendously and he was weighing down on the horn, completely standing up on his feet trying to slow us down," she said.
But the bus was picking up speed.
"The driver realized we were in trouble," Chanasyk said. "We could see the whole thing unfolding."
Four lanes of cross traffic clogged Kearny Street at an intersection below, and the light for traffic on California Street was holding red, Kara said.
She said as the bus hurtled toward Kearny Street, "there was this moment where you realize if the light turns green at that moment, that we had a chance."
But it did not turn green. To avoid the cars crossing the intersection, the driver steered the bus across the double-yellow line and into oncoming traffic, all the while sounding the horn "full blast," she said.
"My mom and I were bracing ourselves. We didn't even know how to position our bodies because we realized there was traffic on all sides."
The driver's quick maneuvering avoided the Kearny Street traffic but put the bus on a collision course with an oncoming car, Chanasyk said.
"I don't think the other passengers knew we had lost our brakes until we swerved into the other lane," she said. "We probably knew a lot sooner than anyone on the upper level."
The driver swerved the bus farther left into the second oncoming lane of traffic and was able to get the bus through another light. By that point, the hill had flattened out and the bus coasted to a stop with what little brake power remained.
"The poor bus driver was completely shaken up," Chanasyk said. "All my mom and I could say was thank you for saving my life."
"All you could smell was burning; burning brakes the whole way," she said.
The company has since taken the bus out of service.
Smith, the City Sightseeing spokesman, said the company's fleet of 36 buses is maintained daily with a routine that involves checking fluid levels, brake functionality and tire air-pressure, Smith said.
He declined to release information about the driver.
Tour buses, such as those operated by City Sightseeing, are licensed by the California Public Utilities Commission. The California Highway Patrol is charged with enforcing requirements for licensing and inspection of vehicles used for chartering tours.
Angela Jackson, director of public relations with the San Francisco Convention and Visitors Bureau, said her office hadn't heard of the incident, but that tourists should feel safe on charter buses.
"There are really strict policies. They're all very well regulated, I can tell you that."
City Sightseeing operates tours in more than 80 locations worldwide, including four major U.S. cities - San Francisco, Los Angeles, New York and Washington, D.C. - and is headquartered in the United Kingdom.