On a cool January day in 2006, I walked onto the street from a hotel in downtown Bangkok and nearly swooned from a visceral sense of deju vu. For a moment, I was back in Saigon circa 1970. It was the smell that did it-a pungent cocktail of two-cycle exhaust, fermented gutter water and street refuse-the unmistakable olfactory presence of an Asian city.If smell is a memory nudge, sound is a sledgehammer and for a Vietnam veteran, none is more powerful than the distinctive rotor slap of a Bell UH-1 helicopter. Heard fading in from the distance, it was the war’s constant soundtrack and only a Huey’s unmistakable wop-wop-wop brings the memories flooding back. For some vets, they are not necessarily always good, for even distant memories are still alloyed with fear.Earlier this month, reader Ed Story sent me an announcement from the Helicopter Association International announcing the final retirement from active U.S. Army duty of the UH-1 in October. Ed was an infantry officer in the Delta in 1969 and in seeing this announcement, I suspect he felt what I felt and what all veterans probably do: A profound sense of respect tinged with sadness.As a military aircraft, the UH-1 was unique for its wide use and its direct contact with virtually everyone in Vietnam. Sure, everyone knew about B-52s and F-4s, but we actually climbed into and flew around in Hueys. In my part of Vietnam, they were just as often called Slicks as Hueys. The origin of the term may be two-fold. Before the AH-1 Cobra appeared in 1967, UH-1s had been fitted with side-mounted guns-improvised gunships. Those without guns were “slick-sided” or just Slicks. The Marine origin of the term may refer to the UH-1’s ability to fly without the internal seat frame arrangement, just a “slick deck.” Either way, the UH-1 made its mark.And so did the pilots who flew it. At Fort Bragg, I served under an E-7 who’d been badly wounded and yanked out of an LZ blasted in the jungle by a 500-pound bomb by a UH-1 shot full of holes. In telling this story, his eyes would glaze a little, but one thing he said about the pilots stuck with me: “Those sons of bitches were crazy.” He meant that as a supreme compliment and nod of respect and nobody hearing the story would take it any other way.The last active Army UH-1 was officially retired at Fort Myer, Virginia on October 2, 2009. As is often case, I wonder if “retired” really means retired. I suspect there must be a couple of these aircraft still doing the special duties only they could do in the Army, and other services still use upgraded versions. A friend of mine-a Vietnam Huey pilot-likes to say that when the last Blackhawk is sent to the boneyard, a crew in a Huey will fly them home.A romantic exaggeration, perhaps, but the UH-1’s legacy lives on beyond its active service. The assault helicopter concept came of age during the Vietnam war and as a result, no other nation in the world uses helicopters and the vertical envelopment doctrine they engendered as well as the U.S. military does. That will be the UH-1’s lasting legacy and any future helicopter will have a tough time matching it.