Then, finally, a faint cry: "Help, help."
Close to a week after his car plunged 200 feet into a ravine, Lavau, 68, was rescued Thursday by his three adult children, who took matters into their own hands after a detective told them his last cellphone signal came from a rugged section of the Angeles National Forest.
As he lay injured in the woods next to his wrecked car, he survived by eating bugs and leaves and drinking creek water, a doctor said.
One of the first things he requested after his rescue: a chocolate malt, his daughter Chardonnay Lavau said on NBC's "Today" show.
Lavau was in serious but stable condition Friday at Henry Mayo Newhall Memorial Hospital with three rib fractures, a dislocated shoulder, a broken arm and fractures in his back, said emergency room physician Dr. Garrett Sutter. He was expected to be released in three to four days after surgery on his shoulder.
Dr. Ranbir Singh, the hospital's trauma director, said Lavau told him he was driving home about 7 p.m. when he was temporarily blinded by the headlights of an oncoming car. He braked, but failed to gain traction. The car flipped and plunged down the embankment.
Lavau said he was unsure if he collided with the car. However, a second car containing a body was found next to Lavau's vehicle. That driver's identity was not released.
Lavau said he did not know if the car was already there or was the oncoming car he had encountered, Singh said.
Lavau spent the night in his wrecked car and crawled out in daylight, finding a stream nearby and eating ants, the doctor said. He found a flare in the other car and tried to light it, but it was expired. He also could not find his cell phone.
Lavau could hear cars and see their lights on the road above and was hopeful he'd be discovered, but as time passed, he grew more uncertain.
"He mentally said goodbye to his family. He wasn't sure anyone would be able to find him," Singh said.
His children told "Today" that after realizing he was missing, they contacted a Los Angeles County sheriff's detective, who was able to narrow Lavau's whereabouts through his most recent cellphone use, text messages and debit card purchases, to the sparsely populated area, about 50 miles north of downtown Los Angeles.
The children then organized themselves into a search party.
"We stopped at every ravine and looked over every hill, and then my brother got out of the car and we kept screaming, and the next thing we heard Dad saying, `Help, help,' and there he was," Lisa Lavau said.
Sean Lavau slid down the embankment to reach his father, who was airlifted to the hospital while firefighters helped his children get back up the ravine.
Lisa Lavau told KABC-TV that while her father was stranded, he used the other driver's eyeglasses so that he could see.
The California Highway Patrol is investigating the accident, trying to establish what happened.
Lavau is expected to make a full recovery and was reported in good spirits.
"He was very desirous of a lobster taco," Sutter said.
Lavau was "super lucky" to have survived, said Dr. Mark Morocco, an emergency room physician at the Ronald Reagan UCLA Medical Center in Los Angeles, who was not involved in treating him but has driven the road.
"He needs to buy a lottery ticket," Morocco said. He added: "The best thing he did was not leaving the site of the crash and getting himself lost in the woods."