Air Force One was designed for presidential multitasking, generations before the word was even invented.
Maybe the funniest example of this concept occurred aboard SAM 26000 at a campaign stop in 1964. Johnson invited reporter Frank Cormier and two colleagues to an impromptu press conference in the plane's bedroom, according to Cormier's book, "The Way He Was."
The president -- who wanted to change clothes after giving a speech in the hot sun -- astonished the reporters when he "removed his shirt and trousers," while answering their questions about the economy. Johnson then "shucked off his underwear" and kept talking while "standing buck naked and waving his towel for emphasis."
Another time on the jet, Cormier wrote, Johnson was sitting and talking with his legs crossed when an "airman who served as LBJ's valet" kneeled before the president and "quickly removed one of Johnson's shoes and socks, bathed the naked foot then put on a fresh sock and replaced the shoe." Neither the valet nor the president ever acknowledged each other, and Johnson didn't miss a beat of his conversation.
The plane carried LBJ's body after his death in 1973, just as it had Kennedy. Twenty-one years later, it ferried Nixon's casket back home to California.
SAM 26000's legacy also includes a footnote labeled, "Monica Lewinsky." The former White House intern who later became a central figure in the impeachment of President Bill Clinton flew aboard the plane as a Pentagon staffer on a tour of European nations in the '90s.
By that time, the aging SAM 26000 had been demoted as a second-tier presidential aircraft and was reserved as a backup. The Air Force introduced a military version of the Boeing 747 -- much bigger than SAM 26000 -- into the SAM fleet beginning in 1990. SAM 26000 carried about 48 passengers and crew, while the new bigger jets held more than twice as many: 102 passengers and crew with about 4,000 square feet of floor space to roam around in.
"It was such a quantum leap forward in Air Force One's capabilities," said Underwood. "With the added ability of inflight refueling, it freed up Air Force One to do whatever it needed to do."
By 1998, SAM 26000 was done. Then-Vice President Al Gore honored the plane's legacy by hosting its final official flight -- a hop from Washington to Columbia, South Carolina, before it traveled to the Air Force museum in Ohio a few months later. "If history itself had wings, it probably would be this very aircraft," Gore said at the time.
As this year's 50th anniversary of the Kennedy assassination approaches, SAM 26000's caretakers at the Air Force museum have no idea how to plan for it. As Underwood put it, "We're just held in limbo right now."
It's a mystery whether Congress will end sequestration in October -- or if even deeper cuts will follow. The Air Force is already preparing for a worst-case scenario.
At the Pentagon, Air Force brass have no plans to change the current funding situation at the museum -- at least through October, said Air Force Lt. Col. Laurel Tingley. After that, she said, "we don't know what the new normal will look like in our current fiscal-constrained environment."
In the meantime, the Air Force "will continue to take action to reduce spending" as a way to support "overseas contingency operations and preserve readiness," Tingley said.
"It's heartbreaking," says Rep. Michael Turner, a Republican member of the powerful House Armed Services Committee who represents the museum's district. "These are incredibly historic aircraft," Turner said, which are inaccessible to visitors because of sequestration that he described as "shameful and outrageous."
Turner called on the Senate and President Barack Obama to come to the table with a solution and break the deadlock.
Despite the closure of the museum's Presidential and Research and Development Galleries, the facility remains open seven days a week, and admission is free.
But until funds appear -- or lawmakers in Washington can come together -- the world's most historic plane will stay behind closed doors.