The B-52 is an Air Force plane that refuses to die. Originally scheduled for retirement generations ago, it continues to be deployed in conflict after conflict. It dropped the first hydrogen bomb in nuclear tests at the Bikini Atoll in 1956, and it laser-guided bombs in Afghanistan in 2006.

It has outlived its replacement. And its replacement’s replacement. And its replacement’s replacement’s replacement.

The bomber, in its 60th year of active service, is slow, primitive and weighed down by an infamy lingering from the carpet bombing of Vietnam in the 1960s. But 76 B-52s make up the bulk of the United States’ long-range bomber fleet, and they are not retiring anytime soon.

The next potential replacement — the Long Range Strike Bomber, which has yet to be designed — is decades away, so the B-52 is expected to keep flying until at least 2040. By then, taking one into combat will be the equivalent of flying a World War I biplane during the invasion of Iraq in 2003.

The unexpectedly long career is due in part to a rugged design that has allowed the B-52 to go nearly anywhere and drop nearly anything the Pentagon desires, including atomic bombs — and leaflets. But it is also due to the underwhelming jets put forth to take its place. The $283 million B-1B Lancer first rolled off the assembly line in 1988 with a state-of-the-art radar-jamming system that jammed its own radar. The $2 billion B-2 Spirit, introduced a decade later, had stealth technology so delicate that it could not go into the rain.

“There have been a series of attempts to build a better intercontinental bomber, and they have consistently failed,” said Owen Coté, a professor of security studies at the Massachusetts Institute of Technology. “Turns out whenever we try to improve on the B-52, we run into problems, so we still have the B-52.”

Officially, the B-52 is called the Stratofortress, but flight crews long ago nicknamed it the BUFF, a colorful acronym that the Air Force euphemistically paraphrases as Big Ugly Fat Fellow.

Too outmoded to be a stealth bomber, the B-52 has become the anti-stealth bomber: a loud, obvious and menacing albatross. It has pummeled armored divisions in Iraq and has laid thunderous walls of destruction over Taliban positions in Afghanistan.

“The big plane was very good,” said one beaming Northern Alliance commander in 2001. In more recent years, it has flown only what the Air Force calls “assurance and deterrence” missions near North Korea and Russia. In 2013, when China claimed disputed airspace over the South China Sea, two B-52s soared through in defiance.

“The BUFF is like the rook in a chess game,” said Maj. Mark Burley, the co-pilot for the training mission over the Great Plains. “Just by how you position it on the board, it changes the posture of your adversary.”

The Air Force is trying to change the image of the B-52 from indiscriminate carpet bomber to precision weapon. Laser-targeting pods, attached to wings of many of the bombers in recent years, allow them to drop guided “smart” bombs. Also in recent years, the big bombers circling high above Afghanistan acted as close air support. “We’re as accurate as a fighter,” said Lt. Col. Sarah Hall, a B-52 pilot who flew missions over Afghanistan.

(With image from Edmund D. Fountain/The New York Times, and writeup from Seattle Times)