Airline passengers can thank fog and a group of trucks for the headaches they experienced during their travels through the Charleston International Airport Thursday and Friday.

A specialized navigation system used to notify passing aircraft of their position was in need of repair after malfunctions prevented its signal from getting through to planes.

That led airlines to cancel all incoming and outbound flights from Charleston — about a dozen in all — leaving passengers in the lurch.

Officials were initially worried that the navigation device, which looks something like an oversize bowling pin, was broken. The system is owned and operated by the Federal Aviation Administration.

But technicians determined Friday that nothing was wrong with the system after performing a fly-by test in which a plane picked up the signal with no problems, the FAA said.

Instead, officials found a much more mundane explanation — a group of construction trucks had parked too close to the system, interfering with the radio signal.

Under clear conditions, pilots also can rely on visual approaches to the airport, but Thursday’s heavy fog didn’t allow for a clear view of the runway, the FAA said.

Someone apparently moved the trucks Friday afternoon, because the navigation system was back up and running by 1:40 p.m., according to the FAA. Flights were back to normal by the afternoon, airport spokesman Becky Beaman said.

The FAA reported that it will work with the Air Force, which owns the runway, to make sure vehicles remain clear of the navigation system in the future.

The hiccup caused delays for several passengers.

Charleston Mayor Joe Riley was among those who couldn’t fly back to Charleston after traveling to Washington, D.C., Thursday to meet with White House and congressional leaders about the pending “fiscal cliff.”

Riley said he got “a robo-call” to his cell phone and ended up staying the night in Alexandria, Va. His trip back was an all-day affair that included flying from Philadelphia to Savannah and driving back, arriving in Charleston shortly before 4 p.m. Friday.

Darren Basicker of Indiana expected to be on a flight from Charleston to Dayton, Ohio, Thursday evening, but his flight was one of those canceled.

Basicker said he was in Charleston on a golfing trip. He checked his golf clubs back in at the airport for a second time Friday morning.

His plane was expected to take off at 11 a.m., despite earlier estimates that incoming and outbound flights would be pushed back until noon.

“I’ll just keep my fingers crossed and see what happens,” Basicker said.

Beaman said some of Friday’s delays were due to several flights returning to Charleston after being diverted to Savannah and Columbia Thursday.

Beaman said the airlines contacted affected travelers Thursday and Friday. She emphasized the significance of passengers supplying their airlines with their cellphone numbers and emails.

“They want to be there to help the passenger,” Beaman said of the airlines.