The sad saga of NBC News anchorman Brian Williams and his fabricated tale of coming under enemy fire while flying in a military helicopter during his coverage of the U.S. invasion of Iraq in 2003 is damning on two levels.

First there was the flawed account, apparently told with varying embellishments over the years, and then came Mr. Williams' lame explanation last week that he had somehow "misremembered" and "conflated" versions of the alleged incident.

Mr. Williams used those words in a memo released by the network announcing he would voluntarily step away from the anchor desk for "the next several days" because it had become "painfully apparent" he has become a distracting news story.

We're sorry, Mr. Williams, but this so-called apology rings hollow, and even if you are the program's managing editor the decision to take a leave of absence should not be your call.

We find it hard to believe anyone would be confused about whether rocket-propelled grenades had forced down your aircraft or a different helicopter an hour earlier, as evidently was the case. It also is inconceivable that Mr. Williams would "conflate," or mistakenly combine details as he retold the story numerous times on the air, most recently during NBC's coverage of a public tribute at a New York Rangers hockey game for a retired soldier who had helped provide security for the grounded helicopters.

Mr. Williams has long been respected for his integrity and credibility, and during his 10-year stint as anchor of "Nightly News" has soared to the top of the network news ratings, seen by about 10 million viewers each evening. Now, unfortunately, his reputation has been irreparably damaged.

Mr. Williams' sins might not have been as flagrant as those committed by New York Times reporter Jayson Blair, forced to resign in 2003 after admitting he had plagiarized and fabricated many of his articles; or Washington Post reporter Janet Cooke, who had to give back her 1981 Pulitzer Prize after confessing making up a profile about an 8-year-old heroin addict; or New Republic writer Stephen Glass, whose numerous articles turned out to be based entirely on fictional events.

Mr. Williams "misremembering" details about a helicopter flight might be less serious than errors by New York Times reporter Judith Miller, whose inaccurate stories about Iraq's weapons of mass destruction helped propel this nation to war, or by Rolling Stone magazine writer Sabrina Rubin Erdely, whose now-discredited article, "A Rape on Campus," apparently falsely described a 2012 attack at a University of Virginia fraternity house.

But a news organizations cannot allow its credibility to be compromised, and Mr. Williams must leave the anchor desk.