In the 10 years or so that Jeromy Smith worked as a flight test engineer at Edwards Air Force Base in Southern California, his wife said, he spoke over and over about the job’s risks.

“He loved his work — as a child, he knew he wanted to go into aeronautics,” Lauren Smith, 30, recalled in an interview on Tuesday about her 32-year-old husband. But as the father of two young children, he also understood the danger inherent to frequent test flights in military aircraft.

“All the time, he would talk about it,” she said.

On Monday, his worst fears came to pass with the crash of a B-52 bomber shortly after takeoff from the base. The aircraft burst into flames, and all eight crew members were killed in the conflagration, which was visible across the Mojave Desert for miles.

The cause of the crash, which occurred at 11:20 a.m. Monday, moments into a routine test mission, is under investigation. Air Force officials, who called it “unsurvivable,” said it could take up to six months to determine what happened.

B-52 bombers, which have been in use by the U.S. military since the 1950s, are known for their immense size, reliability and safety, but also for their advanced age. The test flight on Monday had been part of an Air Force initiative to upgrade the plane’s outdated radar and other avionics, which have long been vulnerable to antiaircraft systems.

Ms. Smith said the flight was supposed to have taken place last Friday, shortly after her husband, a civilian employee of the Defense Department, had returned to work from paternity leave for the birth of their younger son, who is now 4 months old.

She said her husband told her the flight had been delayed for repairs to be conducted, but he did not provide more specifics. “They kept pushing it back, pushing it back, pushing it back,” she said. “And whatever the problem was, it should have been fixed.”

An Air Force spokesman said that “operational security” prevented him from commenting on whether the flight had been delayed for repairs, but he said that test flights “are routinely scheduled and rescheduled” for various reasons, including maintenance and winds.

Ms. Smith, a kindergarten teacher at the Air Force base, about 100 miles north of Los Angeles, was among several relatives of the deceased crew members who posted about their losses online or spoke publicly on Tuesday. Air Force officials said the crew included both members of the military and civilians, and Boeing said two people were its employees. Names were not expected to be formally released until Wednesday under the Air Force’s family notification policy.

Survivors wept on Tuesday as they spoke of the lives lost and the contributions of their loved ones.

Ross Middleton described his brother Miles Middleton, a 50-year-old Air Force veteran and pilot for Boeing who lived near the air base with his wife and two children, as “talented in everything.”

“He was a big brother. He was a father. He was an animal lover. He was a musician. He played viola in the Tehachapi Symphony Orchestra,” said Mr. Middleton, 47, of Aurora, Colo., fighting back tears.

Brianna Estrella, the wife of Lt. Col. Gabriel Estrella, a weapons systems officer at the base, said the loss of her husband had been crushing.

In a social media post mourning his death, she wrote that he “woke up every day excited to go to work” and had been looking forward to Monday’s test flight. “He told me, ‘It’s a once in a lifetime flight, babe.’”

Made by Boeing, the B-52 is both the backbone of the modern Air Force bomber fleet and a relic from a lost era. The jet was designed in the 1940s and entered service in 1955. The Air Force now flies only the newest version — built in 1962.

During the Cold War, the B-52 played a major role in the Pentagon’s so-called nuclear triad, made up of bombers, intercontinental ballistic missiles and submarine-launched ballistic missiles armed with nuclear weapons.

The planes were workhorses during the Vietnam War, carrying up to 60,000 pounds of munitions apiece. The B-52 saw combat again during the 1991 Persian Gulf war and in the war in Afghanistan after the Sept. 11, 2001, terror attacks.

But the military has struggled to keep them in flying condition.

In April, Gen. Stephen L. Davis, commander of the Air Force Global Strike Command, told the Senate that the Air Force was having difficulty procuring spare parts, forcing mechanics to cannibalize parts from other planes.

As of 2025, the Air Force was operating 58 B-52s, out of a fleet of 76.

In these flying fossils, the innards are antiquated and analog. There are banks of dancing dials and aluminum levers. The controls connect to the wing flaps through yards of cable and pulleys. There is a port in the ceiling where the crew can navigate by starlight using a sextant.

When a New York Times reporter flew in one 11 years ago to mark the 60th anniversary of the B-52, the plane’s age was already showing. After sitting in the rain on the runway, the jet — nicknamed “the BUFF,” an acronym for “Big Ugly Fat Fella” in its most polite iteration — had puddles in the cockpit. An engine refused to start.

In mid-flight over the Great Plains, the electrical system went out for several minutes. “This is really the full ‘BUFF’ experience,” the co-pilot said to the reporter with a chuckle as they tried to get the jet running again.

Despite such issues, the B-52 remains remarkably safe and reliable compared to newer jets. Its simple design and eight engines usually allow it to keep flying, even if something goes wrong.

In the last 10 years, the B-52 had a rate of severe accidents that was a fraction of the figure for most other bombers and fighters, according to Air Force safety statistics. The simple design also means that, while more sophisticated modern bombers are often in the shop, B-52s are generally mission-ready.

The Air Force first started talk of replacing the B-52s in the 1960s. Retirement has been put off repeatedly because the proposed replacements for the long-range bomber have been so underwhelming. Some have proven crash-prone. Others have spewed toxic exhaust. Still others suffered from cost overruns.

But the B-52 has evolved to serve in all kinds of missions where the United States controls the air space.

It can carpet-bomb whole areas, as it did in Vietnam. It can carry large numbers of precision bombs and circle for hours, dropping them one by one with laser accuracy, as it did in Iraq and Afghanistan. It can drop tons of leaflets, as it did in the gulf war.

However, the hulking B-52 is extremely vulnerable to surface-to-air missiles, and many were shot down over North Vietnam in the final months of that war.

In March, just a month into President Trump’s war with Tehran, Pentagon leaders were confident enough in their control of the skies that Air Force pilots began flying them over Iran.

The Air Force has said its B-52 fleet is expected to continue flying into the 2050s after “multiple upgrades,” including new engines and radar systems.

Susan C. Beachy contributed research.