LOS ANGELES -- It's the ultimate piggyback ride: A space shuttle perched atop a Boeing 747 as the pair crisscrosses the country.

For three decades, this was how NASA transported shuttles that landed in the California desert to their Florida home base. But it's coming to an end.

This week, four pilots took turns flying a jumbo jet mounted with space shuttle Endeavour on a multi-leg journey bound for Los Angeles where it will go on display in a museum next month.

With the shuttle fleet retired, it's the final ferry mission for a group of highly specialized aviators. The elite pilots over the years have included former astronauts, including famed pilot Gordon Fullerton.

Scores have asked what it's like to haul a 170,000-pound shuttle.

"That's a tough thing to answer," said pilot Jeff Moultrie, who will be in command when Endeavour performs an aerial tour over several California landmarks Friday. "What do you tell somebody? It's different. It's unique."

That's for sure.

For one thing, there's the noise. It is decibels louder inside the shuttle carrier aircraft compared with a commercial airliner because the interior is hollowed out to keep it as light as possible. Aside from a few seats, there are no galleys, overhead bins or even air conditioning.

In case pilots forget they're carrying precious national cargo, the constant vibrations from above jolt them back to reality.

Pilots have to be more careful when they make turns, but otherwise, the 747 handles like a regular plane. They also have to be hyper-vigilant about the weather because moisture can damage the shuttle's delicate tiles.

Built for American Airlines, NASA acquired the aircraft in 1974 and used it for test flights from Edwards Air Force Base in California's Mojave Desert and ferry flights to the Kennedy Space Center in Florida. It obtained a second one in 1990, but it was retired earlier this year.

The four current NASA pilots who can operate the modified 747 are ex-military aviators who split their time flying other planes including zero-gravity aircraft and T-38 supersonic jets.

Even when the shuttles flew routinely, a cross-country lift wasn't always needed. To keep their skills polished, they flew practice flights every several weeks and trained in a simulator twice a year.

Moultrie, who served as a commercial pilot for a decade, said he looked forward most to soaring in close to the Hollywood Sign. Even Angelenos have to keep their distance from the famed sign, which is surrounded by a fence.

"It's bittersweet," he said of the final mission. "We definitely feel privileged to be a small part of history. But on the flip side, we're sad."

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  • Spectators watch as the Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft (SCA) flies near Santa Monica, Calif., Friday, Sept. 21, 2012. (AP Photo/Jae C. Hong)

  • Spectators Mario Vasquez, 40, of Redondo Beach and his son Mario Jr., 2, watch as space shuttle Endeavour, atop NASA's Shuttle Carrier Aircraft, prepares to land at Los Angeles International Airport Friday, Sept. 21, 2012. In a few weeks Endeavour will be towed through city streets to its new home at the California Science Center in downtown Los Angeles. (AP Photo/Ringo H.W. Chiu)

  • Endeavour over the Coliseum

    <a href="http://www.huffingtonpost.com/social/Jennifer_Griner"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/500450686/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Jennifer_Griner">Jennifer Griner</a>:<br />

  • Endeavour in flight

    <a href="http://www.huffingtonpost.com/social/Jennifer_Griner"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/500450686/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Jennifer_Griner">Jennifer Griner</a>:<br />

  • Space Shuttle Endeavour, mounted on NASA's Shuttle Carrier Aircraft (SCA), flies near parasailers in Santa Monica, Calif., Friday, Sept. 21, 2012. (AP Photo/Jae C. Hong)

  • The Space Shuttle Endeavour atop a modified 747 passes the Hollywood Sign and the Griffith Observatory as seen from Dodger Stadium, Friday, Sept. 21, 2012, in Los Angeles. Endeavour will be permanently displayed at the California Science Center in Los Angeles. (AP Photo/Mark J. Terrill)

  • Spectators take pictures as the Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft (SCA) flies near Santa Monica, Calif., Friday, Sept. 21, 2012. (AP Photo/Jae C. Hong)

  • Endeavor, Golden Gate Bridge

    Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft, passes over the Golden Gate Bridge in San Francisco, Friday, Sept. 21, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Marcio Jose Sanchez)

  • Endeavour, Golden Gate Bridge

    Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft, passes over the Golden Gate Bridge in San Francisco, Friday, Sept. 21, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Marcio Jose Sanchez)

  • Endeavour Flyover at NASA/Ames Research Center

    Shuttle flies by Hangar One at Ames, 20 years after Spacelab J flew on Endeavour with experiments from Ames Research Center

  • Shuttle over Austin, TX

    <a href="http://www.huffingtonpost.com/social/skye12"><img style="float:left;padding-right:6px !important;" src="http://i.huffpost.com/profiles/267602-tiny.png?20091021154129" /></a><a href="http://www.huffingtonpost.com/social/skye12">skye12</a>:<br />7:38am flew over downtown Austin after taking off from Houston at daybreak on the way to Ca.

  • Space Shuttle Endeavour

    <a href="http://www.huffingtonpost.com/social/gaewing"><img style="float:left;padding-right:6px !important;" src="http://s.huffpost.com/images/profile/user_placeholder.gif" /></a><a href="http://www.huffingtonpost.com/social/gaewing">gaewing</a>:<br />Over Hayward California

  • Right by American River College, Sacramento CA

    <a href="http://www.huffingtonpost.com/social/Brittaney_Hilleson"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/100000029104891/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Brittaney_Hilleson">Brittaney Hilleson</a>:<br />Great Break from class!!!

  • Endeavor over El Cerrito

    Seen over El Cerrito by Luca and Laila

  • Shuttle Endeavour

    Shuttle Endeavour - Flying over the Mississippi Gulf Coast.

  • Endeavour returns to California

    <a href="http://www.huffingtonpost.com/social/Kelly_Spradlin_Irving"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/748291941/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Kelly_Spradlin_Irving">Kelly Spradlin Irving</a>:<br />Kelly Irving, center, with her children Skylar, 11 and Colin, 7 pose in front of the Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft (SCA) after it landed at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif.

  • Ashely Olson, Alexis Olson, Alyssa Olson

    Ashely Olson, left, poses with her sisters, Alexis, center, and Alyssa in front of the Space Shuttle Endeavour at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif., Thursday, Sept. 20, 2012. Endeavour returned to its California roots after a wistful cross-country journey that paid homage to NASA workers and former Arizona Rep. Gabrielle Giffords and her astronaut husband. (AP Photo/Jae C. Hong)

  • Elizabeth Danirjian, 5, of Santa Clarita, Calif., looks at Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft (SCA) after it landed at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif., Thursday, Sept. 20, 2012. Endeavour returned to its California roots after a wistful cross-country journey that paid homage to NASA workers and former Arizona Rep. Gabrielle Giffords and her astronaut husband. (AP Photo/Jae C. Hong)

  • Mark Kelly

    Astronaut Mark Kelly, husband of former Congresswoman Gabrielle Giffords, talks about watching the space shuttle Endeavour flying over Tucson in honor of the former Congresswoman and Kelly, at the University of Arizona, before continuing its trek west to retirement in a Los Angeles museum, Thursday, Sept. 20, 2012, in Tucson, Ariz.(AP Photo/Ross D. Franklin)

  • Steve Davis, Space Shuttle Endeavour

    Vietnam war veteran Steve Davis take pictures of the Space Shuttle Endeavour at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif., Thursday, Sept. 20, 2012. Endeavour returned to its California roots after a wistful cross-country journey that paid homage to NASA workers and former Arizona Rep. Gabrielle Giffords and her astronaut husband. (AP Photo/Jae C. Hong)

  • Space Shuttle Endeavour sits atop the shuttle aircraft carrier, flies over downtown Austin, Texas early Thursday, Sept. 20, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Marco Hanson)

  • Space shuttle Endeavour sits atop the shuttle aircraft carrier flies over downtown Austin, Texas early Thursday, Sept. 20, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Statesman.com, Alberto Martinez )

  • Space shuttle Endeavour sits atop the shuttle aircraft carrier, passes above Austin, Texas, Thursday, Sept. 20, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Statesman.com, Ralph Barrera) MAGS OUT; NO SALES; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM

  • Space shuttle Endeavour sits atop the shuttle aircraft carrier, passes above the Austin, Texas, skyline Thursday, Sept. 20, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Statesman.com, Ralph Barrera) MAGS OUT; NO SALES; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM

  • Space shuttle Endeavour sits atop the shuttle aircraft carrier, passes by the Texas Capitol in Austin, Texas, Thursday, Sept. 20, 2012. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed. (AP Photo/Statesman.com, Jay Godwin) MAGS OUT; NO SALES; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM

  • Endevour Flyover

    The space shuttle Endeavour, carried atop NASA's 747 Shuttle Carrier Aircraft, passes over neighborhoods near Hobby Airport during a flyover on Wednesday, Sept. 19, 2012, in Houston. Endeavour stopped in Houston on its way from the Kennedy Space Center to the California Science Center in Los Angeles, where it will be placed on permanent display. (AP Photo/Houston Chronicle, Smiley N. Pool, Pool)

  • Endevour Flyover

    The space shuttle Endeavour, carried atop NASA's 747 Shuttle Carrier Aircraft, passes over petrochemical facilities on the Houston Ship Channel during a flyover on Wednesday, Sept. 19, 2012, in Houston. Endeavour stopped in Houston on its way from the Kennedy Space Center to the California Science Center in Los Angeles, where it will be placed on permanent display. (AP Photo/Houston Chronicle, Smiley N. Pool, Pool)

  • Endevour Flyover

    The space shuttle Endeavour, carried atop NASA's 747 Shuttle Carrier Aircraft, makes a low pass over Ellington Field during a flyover on Wednesday, Sept. 19, 2012, in Houston. Endeavour stopped in Houston on its way from the Kennedy Space Center to the California Science Center in Los Angeles, where it will be placed on permanent display. (AP Photo/Houston Chronicle, Smiley N. Pool, Pool)

  • Space Shuttle Endeavour At Ellington Field

    This profile view of the space shuttle Endeavour atop the Shuttle Carrier Aircraft (SCA) at Ellington Field was taken on the morning of Sept. 19, soon after the tandem touched down there. The final component of the former shuttle fleet will be at Ellington for one day and night before continuing to California and its final scheduled stop.

  • Space Shuttle Endeavour Ferried Over Kennedy Space Center

    Space Shuttle Endeavour is ferried by NASA's Shuttle Carrier Aircraft (SCA) over the Kennedy Space Center in the early morning hours of September 19, 2012 as it departs for California. NASA pilots Jeff Moultrie and Bill Rieke are at the controls of the Shuttle Carrier Aircraft. Photo taken by NASA photographer Robert Markowitz in the backseat of a NASA T-38 chase plane with NASA pilot Greg C. Johnson at the controls.

  • Space Shuttle Endeavour Preps for Ferry Flight

    CAPE CANAVERAL, Fla. - Space shuttle Endeavour is towed into the Mate-Demate Device, or MDD, at NASA's Kennedy Space Center in Florida after being backed out of the Vehicle Assembly Building. The MDD is located at the Shuttle Landing Facility at Kennedy. The shuttle will be lifted and connected to the top of NASA's Shuttle Carrier Aircraft SCA, a modified 747 jetliner. The shuttle has been fitted with an aerodynamic tailcone for its flight aboard the SCA to Los Angeles where it will be placed on public display.

  • Space Shuttle Endeavour At JPL

  • The Space Shuttle Endeavour atop a modified 747 flies followed by two chase planes and a bird as near Dodger Stadium, Friday, Sept. 21, 2012, in Los Angeles, on a sightseeing tour of California, the last aerial hurrah before retiring to a Los Angeles museum. (AP Photo/Mark J. Terrill)

  • Endeavour over LA City Hall

    <a href="http://www.huffingtonpost.com/social/Calvin_Fleming"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/608668592/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Calvin_Fleming">Calvin Fleming</a>:<br />Endeavour over LA City Hall

  • Fly-by over Burbank

    <a href="http://www.huffingtonpost.com/social/Christopher_S_Knell"><img style="float:left;padding-right:6px !important;" src="http://i.huffpost.com/profiles/3900473-tiny.png?20120916151551" /></a><a href="http://www.huffingtonpost.com/social/Christopher_S_Knell">Christopher S Knell</a>:<br />Swoop-zoom

  • Space shuttle Endeavour over Griffith Observatory

    <a href="http://www.huffingtonpost.com/social/seanbaello"><img style="float:left;padding-right:6px !important;" src="http://images.huffingtonpost.com/twitter_profile_img/3936480.png" /></a><a href="http://www.huffingtonpost.com/social/seanbaello">seanbaello</a>:<br />Space shuttle Endeavour over Griffith Observatory

  • Endeavor over Downtown

    <a href="http://www.huffingtonpost.com/social/popquizkid"><img style="float:left;padding-right:6px !important;" src="http://s.huffpost.com/images/profile/user_placeholder.gif" /></a><a href="http://www.huffingtonpost.com/social/popquizkid">popquizkid</a>:<br />Shuttle party on Mount Washington!

  • Endeavor over Downtown LA

    <a href="http://www.huffingtonpost.com/social/JordyLoggins"><img style="float:left;padding-right:6px !important;" src="http://images.huffingtonpost.com/twitter_profile_img/3936689.png" /></a><a href="http://www.huffingtonpost.com/social/JordyLoggins">JordyLoggins</a>:<br />Taken from the rooftop of the Weingart Center in Downtown Los Angeles. (Photo Credit: Jordy Altman, @JordyLoggins)

  • Endeavour Shuttle

    Over Hollywood

  • Duck!

    <a href="http://www.huffingtonpost.com/social/JackJason"><img style="float:left;padding-right:6px !important;" src="http://s.huffpost.com/images/profile/user_placeholder.gif" /></a><a href="http://www.huffingtonpost.com/social/JackJason">JackJason</a>:<br />Flying right over us in Runyon Canyon, you can see the tiles on the underside of Endeavor

  • Endeavor in Hollywood

    <a href="http://www.huffingtonpost.com/social/JackJason"><img style="float:left;padding-right:6px !important;" src="http://s.huffpost.com/images/profile/user_placeholder.gif" /></a><a href="http://www.huffingtonpost.com/social/JackJason">JackJason</a>:<br />A real star arrives in Hollywood.

  • Space Shuttle over Lancaster CA

    <a href="http://www.huffingtonpost.com/social/seenitall"><img style="float:left;padding-right:6px !important;" src="http://i.huffpost.com/profiles/91522-tiny.png?20110209134610" /></a><a href="http://www.huffingtonpost.com/social/seenitall">seenitall</a>:<br />Space Shuttle flying over our house this morning in Lancaster CA

  • Endevour Shuttle

    Over Hollywood

  • Endeavour Over Capitol Records

    Space Shuttle Endeavour flies over Hollywood before landing at LAX

  • Shuttle Endeavour

    Shuttle Endeavour - Flying over the Mississippi Gulf Coast.

  • Endeavour and Flock

  • Surfers Welcome Endeavor

    <a href="http://www.huffingtonpost.com/social/jiggystyles"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/1171807866/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/jiggystyles">jiggystyles</a>:<br />Geoff Mann and Benj Thall Surf underneath Space Shuttle Endeavor as it begins it's tour of Los Angeles.

  • Surfers Welcome Endeavor to LA

    <a href="http://www.huffingtonpost.com/social/jiggystyles"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/1171807866/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/jiggystyles">jiggystyles</a>:<br />Geoff Mann and Benj Thall Surf underneath Space Shuttle Endeavor as it begins it's tour of Los Angeles.

  • Shuttle over Universal City

    <a href="http://www.huffingtonpost.com/social/Tad_Wadhams"><img style="float:left;padding-right:6px !important;" src="http://graph.facebook.com/1192147724/picture?type=square" /></a><a href="http://www.huffingtonpost.com/social/Tad_Wadhams">Tad Wadhams</a>:<br />

  • Endeavor

    <a href="http://www.huffingtonpost.com/social/jesse99"><img style="float:left;padding-right:6px !important;" src="http://i.huffpost.com/profiles/2444643-tiny.png?20111203235246" /></a><a href="http://www.huffingtonpost.com/social/jesse99">jesse99</a>:<br />Nasa Shuttle Endeavor