FAA leans on airport to fix towers

0 Comments | La Crosse Tribune, Jun 25, 1998

They may not be as noteworthy as the Leaning Tower of Pisa, but the leaning airport landing approach towers of Lake Onalaska are significant.

The La Crosse Municipal Airport has had 13 towers in the water for about 25 years. Three of the towers will be removed because they are no longer needed, and out of the remaining 10, seven are tilting.

The Federal Aviation Administration has given the airport until the end of 1999 to fix the problem. Airport Manager Michael Daigle's goal is to have them repaired by fall of 1999.

The towers are crucial to the airport because they hold lights that help guide pilots as they land planes. The lights atop the leaning towers have been adjusted as much as possible to cast light in the required area. The only option left is to fix them.

The anticipated cost of repair is about $2.5 million, and Daigle has requested discretionary funding from the FAA to pay for 90 percent of the cost. The state would then pay 5 percent, with the remaining 5 percent coming from the city of La Crosse and the airport.

But fixing the towers involves more than meeting the airport's needs. Because the towers are in the water, there are many agencies involved, including the Department of Natural Resources, U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.

"Ideally, if we can find a solution that would help the lake, help the DNR, help the Corps of Engineers, we're all for that," Daigle said.

The U.S. Army Corps of Engineers is concerned that there would be too much water flowing past the bases of the towers if they are too large. The corps wants to maintain the balanced flow, said Bruce Norton, biologist with the corps.

But the corps also realizes the airport has to maintain its towers and wants to try to balance that with the water resource impacts, he said.

DNR Mississippi River fisheries biologist Mark Endris is interested in keeping the water in the fish channels moving as slow as possible.

"We understand the towers need to be fixed, but we want it to have minimum impact on the fish habitat project that's adjacent to the area," he said.

The steel towers are driven into the silt surface of the lake between the airport and Rosebud Island.

Over the years, the towers began to lean, likely due to a combination of ice pushing on the towers in the winter and weak soil conditions, said Andy Platz, vice president and manager of aviation services for Mead & Hunt, Inc., which is working on the project.

Lights on the towers tell the pilots where they are in relation to the runway and are at a standard spacing that pilots are trained to recognize, Daigle said.

"It's a fairly crucial time to the pilot to be able to recognize where he is in relation to the landing environment and be able to transition from flying off instruments in his cockpit to looking out the window and landing the airplane smoothly and safely onto the runway," he said.

The lights on the towers have to be in a specific spot in a tight, circular area. As the towers continue to lean, the adjustment brackets that hold the lights are almost at the very limit. The lights are adjusted when necessary and are checked monthly. If adjustments are no longer able to be made within the allowable pattern, Daigle said, the lights would have to be shut off.

If the lights are off, there would be certain times that airplanes wouldn't be able to land, such as when there is fog, because pilots couldn't make the transition from using flying instruments in the cockpit to landing the plane visually, Daigle said.

When the lights aren't on, the visibility requirements to make a landing have to be increased.

The FAA expressed concern about the towers, one being the safety of the people who adjust the lights. A couple of the towers are almost leaning over backward, so Daigle had the ladders on those towers straightened. The FAA is also concerned that if the lights fall out of alignment, the FAA and Daigle don't have any choice but to turn them off.

Although still in the preliminary stages, Mead & Hunt is looking at scaling back the size of the towers, Platz said. He said he hopes for a similar design to the existing towers, but ones that would have a 40-year design life. The towers would be rebuilt and existing equipment would either be transferred or the FAA may install new equipment, he said.

Platz's firm also would do a hydrology study on how to minimally affect the flow of the channel so the fish habitat would not be disturbed. Eventually, Mead & Hunt would do an environmental assessment.