Navigation system an issue with runway rebuilding project

Airline passengers might get diverted to other airports if the cloud cover is too low while the main runway at Charleston International Airport is being rebuilt next year.

That's because the secondary runway lacks an instrument landing system, which has directional transmitters that send out radio beams to guide planes in limited visibility.

Charleston Air Force Base, which owns the runways, doesn't plan to install one. It has a mobile microwave landing system for military aircraft only and is not permitted to spend money on items that are not part of its mission, base spokesman Capt. Frank Hartnett said.

"The FAA is responsible for procuring and maintaining navigational aids for civilian aircraft," he said.

The Federal Aviation Administration responded that it's the Air Force's responsibility since it owns the runways. FAA spokeswoman Kathleen Bergen said the agency has no plans to install a temporary ILS on the secondary runway during the nine-month runway reconstruction project.

"There has been some discussion for the Air Force to obtain funding for an ILS and work through an FAA contract to purchase that equipment," Bergen said.

But as of Friday, airports director Sue Stevens said: "There are no plans to put an ILS on the secondary runway."

She added that does not mean that aircraft cannot operate safely at Charleston International.

"There are other navigational aids that aircraft use in addition to the ILS, and those are available on the secondary runway," she said.

As with the ILS, the other system has limitations as well.

If cloud cover falls to 286 feet or less above the ground and there is less than three-quarters of a mile of visibility, it is generally not safe for aircraft to try to land or take off, Stevens said.

"If the interstate is fogged in and you can't see two feet in front of you, you can't safely operate your vehicle," she said, using an analogy. "There are extreme weather conditions when aircraft cannot operate safely, just like driving a car. That is possible with every airport across the country, regardless of the navigational aids they have."

In those instances, she said the pilot makes the decision and might decide to divert to another airport.

Pilots, such as those at Delta Air Lines, a major carrier in Charleston, are trained to fly in poor weather, including thick fog and lingering low clouds, Delta spokesman Anthony Black said.

"Depending on the known conditions, we would either delay the takeoffs or divert and wait for a clearing in the weather," he said.

US Airways has a similar policy.

"If the cloud cover goes below a certain level, you are going to divert to another airport," said US Airways spokeswoman Michelle Mohr.

The Air Force said Charleston averages about 28 days a year when an ILS might be required for some part of the day, usually at night.

"Typically, those conditions are most prevalent in the winter and spring when cold air gets banked up against the Appalachians and clouds sit between there and the coast," said meteorologist Steven Taylor of the National Weather Service in Charleston.

"When it does happen, it tends to have a significant impact on aviation," Taylor added. "It's usually during the overnight hours. It's rare for us to stay below 400 feet for long during the day. Once the sun comes up, it usually last two or three hours, but it can last longer."