A runway at Florida’s Tampa International Airport is scheduled to reopen Thursday with new numbers and signage to account for the gradual shift of the Earth’s magnetic North Pole.

Runway 18R/36L, which runs north-south, has been closed since January 3 for numeric redesignation of the compass headings at each end of the runway and to change taxiway signage to account for the one-degree shift.

It will reopen tomorrow as 19R/1L, indicating its alignment along compass headings, FAA spokeswoman Kathleen Bergen said.

Every five years, the FAA reevaluates shifts in the poles – its magnetic variation – and makes changes to runways and flight procedures as needed, Bergen said.

The FAA also publishes new aeronautical charts for pilots every 56 days, and with the next one due on Thursday, it made sense to make the changes at Tampa International Airport effective the same day, she said.

“The Earth’s magnetic fields are constantly changing,” she said. “It’s a very dynamic system so we make these changes effective every 56 days.”

Redesignation of runway compass headings is a common practice that occurs whenever the Earth’s magentic fields change, she said. It happened last year at Palm Beach International Airport and is scheduled to happen at the Tampa-Clearwater International Airport later in 2010, she said.

(Source: CNN)