If you looked up at the sky on Friday morning, you may have seen some strange flight patterns left by jet contrails above Vancouver and Portland.
It was caused by planes inbound for Seattle-Tacoma International Airport being delayed by Seattle’s heavy fog, according to Perry Cooper, spokesman for Sea-Tac.
The National Weather Service tweeted on Friday that planes were circling above Portland because if the planes ran low on fuel, they would be able to land at Portland International Airport for refueling.
“This happens whenever we have backups with fog,” he said. “This was probably the first time folks had seen them.”
Sea-Tac has been experiencing heavy, low fog all week, Cooper said, causing many aircraft to fly in “holding patterns” while air traffic control slows down the number of inbound flights for safety reasons. The airport typically sees 44 to 48 planes an hour, but with fog, the airport can only take about 20 to 24 an hour.
“It reduces the amount of air traffic you can bring into the airport,” he said.
On Friday, the fog at Sea-Tac reduced visibility to about 200 feet, Cooper said.
On Monday, Sea-Tac had worse fog, and it delayed 462 flights. Cooper said Friday’s fog likely caused about the same number of delays, but the airport had not calculated it as of Friday afternoon.
About 1,300 flights arrive at Sea-Tac every day, he said.
He also gave caution to travelers who see fog in the morning: “If you start to see fog in the morning and you have a flight, reach out to your airline and see if your flight is delayed,” he said.
