Even the most frequent flier may relax just a bit when the wheels of a jetliner touch down on the runway. But the risks of flying - however slight statistically - don’t end with a smooth landing.

Industry officials and regulators say taxiing around an airport, especially one as big and busy as Atlanta’s, involves hazards of its own.

Last year Hartsfield-Jackson International Airport logged 18 incidents on runways or taxiways. They ranged from jets that were on or too close to runways being used by another plane, to fenderbenders between wingtips or tails, to a ground vehicle going where it shouldn’t.

Such incidents are exceedingly rare when considered against Hartsfield-Jackson’s 920,000 annual operations. Over the past five years the number has bounced between a high of 23 in 2007 and a low of 14 in 2009.

Still, the potential for disaster with so many huge machines moving around so close together keeps ground accidents high on the list of safety concerns. Recent incidents elsewhere include one last month at Washington Dulles International Airport, in which a Lufthansa Airbus 330 jet’s wing hit the tail of a small Colgan Air plane while taxiing.

Airports and regulators closely track runway incidents, upgrade alert systems and try to improve airfield layouts to lessen the risks. Delta Air Lines, which operates the world’s biggest connecting hub in Atlanta, said it has a special emphasis on airfield safety, including a focus on situational awareness and constant communication.

Risk will exist “as long as you have human intervention,” said Balram Bheodari, Hartsfield-Jackson’s deputy general manager. Pilots or vehicle drivers on the airfield may lose situational awareness and enter runway areas when they shouldn’t, he said.

Hartsfield-Jackson spent millions to build an “end-around” taxiway in 2007 to eliminate 600 to 700 runway crossings a day. It has also changed procedures to reduce the number of times arriving planes cross in front of planes waiting to take off by about 600 times a day, according to the Federal Aviation Administration.

Another “end-around” is being discussed, and a previously announced project to install runway “traffic lights” is also planned.

Hartsfield-Jackson also focuses heavily on training workers who drive vehicles on the airfield, which to the untrained eye can be a maze of intersections, multicolored lights and coded signage.

Even veteran pilots can become confused. In 2009 a Delta 767 landed on a taxiway, a potentially disastrous foul-up that stemmed from a series of in-flight problems exacerbated by lighting issues on the ground.

Following an investigation, the National Transportation Safety Board suggested the FAA review whether an alert system to warn of taxiway landings could be added to the airport traffic management system. It also suggested directives to ensure proper ground lighting settings.

The FAA said it would form a work group on lighting, and Hartsfield-Jackson plans to upgrade all taxiway lights by 2015 to LED technology instead of having a mix of LED and incandescent lights that can confuse pilots. Prospects seem dim for an alert system specifically for potential taxiway landings, which the FAA said could conflict with alerts for the more likely problem of landing on the wrong runway.

Meanwhile, the FAA has noted four runway “hot spots” at Hartsfield-Jackson, including intersections of taxiways and runways that can confuse pilots. It has asked Hartsfield-Jackson to review the entire airfield as part of its ongoing master plan update, to look for potential issues.

Hartsfield-Jackson had fewer runway and taxiway incidents last year than some other airports, including Chicago O’Hare and Los Angeles International. One advantage in Atlanta: all five runways are parallel, reducing the need for crossings that raise the risk of incidents. Another is experienced air traffic controllers and pilots.

In one incident last year an Airbus A320 jet taxied past the line where it was supposed to stop, and came within about 140 feet of the edge of the runway before stopping, while a Canadair CRJ-200 regional jet was departing from the runway.

In another, an MD-88 was still taxiing down the runway after landing when a second one was attempting to land behind it. The second plane had to do a “go-around.”

But all of Hartsfield-Jackson’s runway incidents last year were ranked as category C or D, lower levels signifying a potential hazard but with ample time and space to avoid it.

Even so, Bheodari said, “when you run a stop sign, you may not hit someone, but there are repercussions. The same with a runway incursion.”

Tracking less-serious incursions can provide guidance to prevent worse incidents, said Paul Deres, director of education for the Aircraft Owners and Pilots Association Foundation’s Air Safety Institute.

“If we see where pilots have problems, even at low risk levels,” he said, “we can find opportunities for education to improve runway safety.”