Runway 8L-26R was previously labeled 7L-25R but a shift in the Earth's magnetic field forced a re-designation effort by crews at Long Beach Airport. Photo Courtesy of Long Beach Airport

Two of Long Beach Airport’s runways were re-designated this week due to changes in the Earth’s magnetic field.

The changes took effect Thursday morning on the two smaller runways that are parallel to one another  at the airport. The pair are used primarily for general aviation but the northernmost runway is sometimes used as a secondary runway for commercial flights.

The city said the changes were prompted by natural shifts in the Earth’s magnetic field.

Formerly labeled 7R-25L and 7L-25R, the two runways have been re-designated 8R-26L and 8L-26R respectively. The runway numbers are based on their magnetic headings depending on the side they’re being approached from. Pilots depend on magnetic headings to orient themselves and their aircraft for takeoffs and landings.

The two parallel runways at Long Beach Airport (highlighted in red) were relabeled by crews at the airport this week after a natural shift in the Earth’s magnetic field put them out of synch with pilots’ compasses.

For instance, if approached from the east, the northernmost runway (8L-26R) would be at 260 degrees on a compass and on the right (26R) of an incoming plane. If the same runway were approached from the west it would be at 80 degrees on a compass and on the left (8L) to the incoming plane.

The changes’ impact will not be felt by the general public, Long Beach Airport spokesperson Stephanie Montuya-Morisky said. “But it will be felt by pilots and air traffic controllers who rely on the correct designation of the runways.

“It’s the airport’s responsibility to work with the FAA to maintain a safe runway environment in order to continue commercial traffic,” she said.

A release by the city noted that it’s a rare instance for the airport to have to re-designate runways. In a statement, Mayor Robert Garcia said it appears to have been the first time in nearly 70 years that the airport has had to undertake such a task.

The city’s release said it took a crew five nights to update the runways, changing the markings on the pavement as well as the electrical signage that pilots look to to ensure they’re on the right path. The southernmost runway, 8R-26L is temporarily closed but is expected to reopen in the fall.

The city estimated that the updates, taken out of an FAA grant that was approved by the City Council last year. cost about $45,000.

“Runway markings are crucial to airport safety,” Long Beach Airport Director Jess Romo said in a statment. “It takes a tremendous amount of coordination for this undertaking. Thanks to the efforts of everyone involved—our airport facilities, operations and engineering teams, our construction partners, and the FAA—the overnight transition ran smoothly.”

Jason Ruiz covers City Hall and politics for the Long Beach Post. Reach him at [email protected] or @JasonRuiz_LB on Twitter.