America’s unifying moments have emerged, during these weeks of hunkering down against the coronavirus, as one of the things we treasure as we scout the World Wide Web. We find them moving and uplifting, or sometimes just funny. Some have been famous for decades, and some less so. Some aren’t available on the Web. There are, though, wonderful moments.

Like the officer of Free Vietnam who, with the communists closing in and on the hunt for people like him, suddenly moved to save his family. He was a pilot of the big twin-rotor helicopters known as the Chinook, workhorses of the war. He swooped in and plucked his family from a dusty playground, and flew out to sea, with a few gallons of fuel and a full tank of prayer.

Suddenly, an American warship becomes visible beneath the clouds. What happened next is captured by Rory Kennedy in her absolutely riveting documentary, “Last Days in Vietnam,” about the desperate effort to save citizens of Free Vietnam who sided with us during the war. Ms. Kennedy turned up film and photographs and recorded first-person interviews of the events.

At one point, the pilot’s wife drops her one-year-old baby out of the Chinook while it is frantically hovering over a warship moving on the main. When everyone is out, the pilot hovers with his wheels in the water while struggling to get himself out of his heavy flight suit. This section of Ms. Kennedy’s documentary is just breathtaking.

We first watched the film in a roomful of veteran military and diplomatic officers and newspapermen and women who — both hawks and doves — had been invested emotionally in Vietnam. As the father’s gamble played out on the film, some members of the audience held their hands to the sides of their heads. Others clasped a hand over their mouths. The suspense was such that some pinched their own foreheads as they watched a real-life race for American freedom.