Donald J. Trump was doubling down on Friday about his story of nearly crashing during a helicopter ride once with Willie Brown, the notable Black California politician.

He was so adamant that it had happened that he threatened to sue The New York Times for reporting that the story was untrue, then posted on his social media site that there were “‘Logs,’ Maintenance Records, and Witnesses” to back up his account.

“It was Willie Brown,” Mr. Trump, who spent much of the last year hoping to make gains with Black voters, posted. “But now Willie doesn’t remember?”

Mr. Brown, 90, who was mayor of San Francisco and speaker of the California Assembly, gave several interviews on Thursday and Friday saying such a trip never occurred.

Turns out, however, that there was a Black politician from California who once made an emergency landing in a helicopter with Mr. Trump. It just wasn’t Mr. Brown.

Nate Holden, 95, a former Los Angeles city councilman and state senator, said in an interview with The Times that he had been on a helicopter ride with Mr. Trump around 1990 when the aircraft experienced mechanical trouble and was forced to make an emergency landing in New Jersey.