ST. LOUIS — The airplane carrying Democratic presidential candidate Barack Obama made a safe, unscheduled and precautionary landing in St. Louis today after a flight control problem arose en route from Chicago to Charlotte, N.C.

The plane, an MD-80 Midwest charter, experienced a problem maintaining the proper pitch, or control over keeping the nose at the proper angle, as it was taking off from Chicago, the pilot said.

Laura Brown, an FAA spokeswoman, said the plane did not declare an emergency, but simply "requested a diversion for mechanical issues they called a flight control problem."

As the plane was being evaluated on the ground here, Obama was reading the paper in the front of the plane, but ventured briefly to chat with the press at one point.

"I just thought we'd spice things up a little bit today," Obama said, smiling and joking.

Earlier while airborne, passengers had felt the plane dip briefly, causing a stomach-rolling sensation as if being in a roller coaster, but the unexpected movement did not cause visible alarm for the frequent fliers on the plane.

About an hour after taking off from Chicago, reporters among the 44 passengers on board were made aware of the problem. A flight attendant, who was clearing the aisles, told reporters the plane wasn't heading to North Carolina as planned.

Minutes later, Obama spokeswoman Linda Douglass came to the back of the plane to inform reporters of a "minor little problem with the airplane" and said the plane would make a precautionary landing in St. Louis.

Then, the pilot came on the overhead speaker and provided more details.

"We detected a little bit of controllability issue in terms of our ability to control the aircraft in the pitch, which is the nose up and nose down mode," announced the pilot, whose name was not released in accordance with Midwest policy.

"The autopilot and the aircraft are just fine. As we descended, whatever was inhibiting our ability has now been rectified. However, just for safety purposes we are going to be stopping in St. Louis and making sure that there's nothing binding our controls. We have full authority of the aircraft. We will not need to brace. It will be a normal landing," he said.

The landing at 9:51 a.m. CDT, was, in fact, normal.

A mechanic was traveling on the plane at the time, and was inspecting the problem on the ground in St. Louis.

Obama, his staff, the Secret Service entourage and the press sat on the plane as it was being checked out at Signature Flight Support, a facility which handles private jets, at Lambert Airport.

During his visit with reporters, Obama shook his head "no" when asked if he was worried.

"Anytime a pilot says something's not working the way it's supposed to, then you make sure you tighten your seat belt," Obama said. "Everything seemed under control. The pilots knew what they were doing."

Obama's campaign charter hasn't made a precautionary landing before.

"This is a first," he said, and then returned to the front of the plane to confer with staffers.