Poles blamed for airport problem

Published: Wednesday, February 17, 2010

Insulators on electric power poles apparently are largely to blame for the interference that jammed the instrument landing system at Lubbock Preston Smith International Airport nearly two weeks ago.

The next move for technicians from the Federal Aviation Administration and Federal Communications Commission is to identify the sources that could raise havoc with radio signals pilots need to land safely when visibility is poor.

No single source of signal problems has been identified, FAA spokesman Lynn Lunsford said Tuesday, adding "It's more a number of little things related to power poles."

"It's just a function of the climate and the area, the dry, cold weather conditions you have in Lubbock," he continued. "We tend to see it where power pole components expand and contract with the weather. When they get loose, you see some evidence of arcing."

The electrical arcing can create static that interrupts the ILS signal in the same way lightning in an area can overpower AM radio signals.

And because the problem involves power lines, he said, it's less likely to happen when the air is calm.

"On a windy day, we could find a lot of potential sources, but not all of them are causing the problem," he said.

Pilots have been asked to monitor their ILS receivers as they land, which is something they wouldn't normally do in good weather.

Incoming flights usually approach the airport's 11,500-foot-long main runway from the north, and the ILS beacons are oriented that way.

But prevailing winds over the past two days have meant airplanes are approaching Preston Smith from the south - which pilots call "flying the back course" - and testing a weaker version of the ILS signal, Lunsford said.

Some flights Tuesday landed on the airport's east-west runway, he added.

In addition to reports from the FAA's check aircraft, officials have been asking pilots to monitor their ILS receivers on their airplanes and describe any unusual experiences, and working with instructors at two airport flight schools who have been teaching students how to use the instrument system.

"Before we turn this thing loose and pronounce it fixed, we want to have an adequate opportunity for a number of airplanes to come in," he said.

Because approaching pilots have been flying in from the south, the federal technicians have been looking on real estate beyond the south end of the runway for interference sources.

To comment on this story:

walt.nett@lubbockonline.com l 766-8744

charles.reinken@lubbockonline.com l 766-8706

LUBBOCK/FAA, FCC working to find solution

