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, the aircraft was acquired by NASA in 1974 and used for test flights from Edwards Air Force Base in California's Mojave Desert and ferry flights to the Kennedy Space Center in Florida. NASA 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."