Boeing 747 planes become Air Force One when the commander in chief is aboard. The current planes are getting old, and the Pentagon wants to buy new ones. CBS News' Mark Albert reports from behind the scenes on how for the first time the military may buy three 747s to replace the current two.

Air Force One is the most recognizable aircraft in the world: six stories tall, two-thirds of a football field long and carrying immeasurable prestige.

More than "Hail to the Chief," more than the ubiquitous Secret Service agents, even more than the famous seal, there is no more identifiable symbol of the mobile presidency than Air Force One.

"It has come to represent the power of the American presidency, the reach of the American presidency," author Ken Walsh said. "It's come to symbolize American technology and America's technological prowess."

Walsh wrote a book on Air Force One and has covered the past five presidents for U.S. News and World Report. He's flown on Air Force One about 300 times, which begs the question, what's it like to fly on the presidential aircraft?

"For a president, it's fabulous," Walsh said with a laugh. "When they left office, the four who've left office say the thing they miss the most is Air Force One."

But under their polished exterior, the two aircraft that commonly serve as Air Force One are aging, now a quarter-century old. Even though both Boeing 747-200s have only flown a fraction as much as a commercial 747 of the same age, the Air Force says it's time for a new generation of presidential wings.

"We've got a pretty good size team working on it," Air Force Col. Amy McCain said.

McCain is in charge of ordering the new Air Force One.

"The current airplane was fielded in 1991," McCain said. "It's the only 747-200 left in the United States that is flying. So it costs a lot more time and money to keep that airplane flying than it used to. It's actually cheaper in the long run to replace it."

McCain's team has grown from 20 people to 80 in just the past year. It will soon expand to 100.

In January, the Air Force announced its intention to use Boeing's 747-8 airframe.

The long-range, wide-body aircraft is made in Everett, Washington. It comes with a longer fuselage, greater wing span and new engines and avionics. It will be heavily modified with all of the latest technological and security gear. But this symbol of America doesn't come cheap.

Updated budget documents show the military's request to Congress starts with $102 million this year, and the numbers quickly gain altitude to more than $3 billion in total in the next five years. And that's not counting the final three years of the project.

Some say that the aircraft does not need to be replaced and that the taxpayers simply can't afford to buy a new presidential plane.

"The top priority is an affordable aircraft that will meet the presidential requirements," McCain said. "We're buying up to three. It depends on all the availability of having two airplanes available for the president at any one time."

If the deal takes off, the current Air Force One will likely land in the National Museum of the U.S. Air Force in Dayton, Ohio, home to nine presidential aircraft.

The museum's historian, Jeff Underwood, said the history of the presidential aircraft is filled with triumph and turbulence.

Franklin Roosevelt was the first to fly while in office. The plane the president took to Yalta in 1945 had an electric-powered elevator.

The four-engine Douglas plane, code-named "The Sacred Cow," was modified for the president, who was stricken by polio at age 39.

Roosevelt flew on the plane only once before his death. Harry Truman then used it, signing the act that created the Air Force.

The Boeing 707 that took the first American president to China is at the museum. It carried eight presidents over 36 years.

Jackie Kennedy approved the now-iconic blue and white design still in use today.

The 707 also flew the Kennedys to Dallas and President Kennedy's successor back to Washington.

The original log book from that date shows the one flight with two presidents, after Lyndon Johnson took the oath of office in a packed, sweltering cabin.

The headwinds of history buffeted George W. Bush aboard Air Force One on 9/11 as the plane became an airborne refuge after the terror attacks.

In 70 years of presidential flight, Underwood said the unique set of aircraft we now know as the Air Force One has taken the country to new heights.

"This is not just the president's plane," Underwood said. "This is the plane that belongs to the people of the United States. When you look on the side of the airplane, it tells you, United States of America. This is a symbol of the United States, and we are the people of the United States."

The Air Force hopes to sign the first contract with Boeing later this year for the next Air Force One. The goal is to have the new 747s flying the president eight years from now in 2023.