What the news media grabbed onto was something well known to pilots and navigators: the earth?s magnetic field is changing. Magnetic north is distinct from the geographic North Pole, of course, but magnetic north is proving to be an increasingly moving target. At the moment, it?s sliding across the Arctic Ocean near Canada toward Siberia at a rate of nearly 40 miles per year. According the U.S. Geological Survey, that speed has increased by 36 percent over the last 10 years.

?Adjustments to runways like this and to navigational aids are ongoing,? according the Kathleen Bergen, a spokeswoman for the FAA Southern Region. ?Every five years, the FAA reevaluates shifts in the pole?its magnetic variation?and makes changes to runways and flight procedures as needed,? she said.

Mike Pound of Jeppesen noted that his company provides immediate updates to subscribers on airport changes, whether they are listed in databases, charts or approach plates. ?It?s an ongoing process for us but, to be perfectly honest, it?s also nothing new. Airports change their runway designators regularly.?

The same change took place in 2009 at Palm Beach International Airport (PBI), and Miami International (MIA) corrected its north runway numbering when it was rebuilt in 2003. Mike Nonnemacher, director of operations at Fort Lauderdale International (FLL), says they plan to renumber their south runway during a 2014 expansion. The St. Petersburg-Clearwater International Airport (PIE) is scheduled for a change later this year.

One reason for the flurry of re-paints in Florida is that the state lies on the agonic line through the United States, which is the line with no magnetic variation. The agonic line presently runs roughly from Florida through Lakes Michigan and Superior to the magnetic north pole. Compasses used along that line require no variation, but the line is moving west along with the pole, leading to runway closures for renumbering.