Thousands of passengers were grounded Saturday during a snowstorm at Reno-Tahoe International Airport (search) on its busiest weekend of the year.

At nearby Lake Tahoe (search) and elsewhere in the Sierra Nevada, the storm dumped up to 18 inches of snow and delayed thousands of Thanksgiving holiday motorists heading over mountain passes.

Sixty-nine flights at the airport were canceled or delayed during a seven-hour period Saturday after a malfunction in equipment used to guide pilots when visibility is poor, spokesman Brian Kulpin said.

The instrument landing system is maintained and operated by the Federal Aviation Administration, which fixed the problem after the storm had left up to 6 inches of snow in Reno.

Travelers were urged to contact their airlines before heading to the airport because delays were expected to continue. Kulpin said some passengers might not be able to get a flight from Reno until Tuesday because flights are booked solid Sunday and Monday.

"This has such a ripple effect throughout the system," Kulpin said. "It has impacts on other airports because there are people stranded at other airports."

The Sunday after Thanksgiving traditionally is the airport's busiest day of the year, with about 10,000 passengers using the facility.

Kulpin said airport officials were livid because it was the second time this month the instrument landing system malfunctioned during a storm.

"This is an awful way to treat the flying public and it's all because of the FAA," he said.

FAA spokesman Allen Kenitzer in Seattle said a combination of bad weather and equipment failure caused the FAA to suspend flights in and out of the airport.

The cause of the equipment failure is under investigation, but it appears a heavy buildup of snow on an antenna contributed to it, he said. The storm restricted departures by causing planes to have to undergo deicing, he added.

"Believe me, we understand the people's frustrations and we appreciate their cooperation during the delay," Kenitzer said. "But safety is our number one priority and safety was never compromised during this time."

The storm also caused problems on the highways. Authorities reported more than 100 minor traffic accidents in the Reno-Tahoe area, and said a stalled bus on I-80 near Truckee, Calif., backed up eastbound traffic.

The storm knocked down electrical lines in several Northern California counties and left nearly 11,000 customers without power, including 6,700 in Oakland and Berkeley, and 2,100 in Carmel. Sierra Pacific Power Co. officials reported small, scattered outages affecting hundreds of customers in the Reno-Tahoe area.

In Southern California, the storm brought less than a quarter-inch of rain in most areas but was blamed for one death. A car ran into a tree that was toppled by gusting winds in Lancaster north of Los Angeles, killing the driver and injuring a 16-year-old passenger, according to the Los Angeles County Sheriff's Department.

Meanwhile, in Ontario, the driver of a tractor-trailer was killed when he lost control of the vehicle in the rain, plunging over the side of a highway, according to the California Highway Patrol.

In San Diego County, high winds forced a sheriff's helicopter to give up an attempt to rescue two hikers stuck in the Santa Rosa Mountains near Borrego Springs. A ground crew was expected to rescue the hikers, one of whom had a broken leg.

Rainy conditions also prevented helicopters from continuing a search for a missing hiker in the Los Padres National Forest.