Two F-15C fighters from the Oregon Air National Guard's 142nd Fighter Wing were likely the cause of booms heard Tuesday in the vicinity of Seattle, Wash., during a presidential visit. The Oregon National Guard confirmed Tuesday that its NORAD-directed fighters were cleared to go supersonic to intercept what was later found to be a float-equipped Cessna 180 with two aboard as it wandered near a presidential TFR. The jets, which departed from Portland International Airport, did not arrive on scene in time to meet the aircraft, but sonic booms can be heard in videos taken near Seattle at the time and seen on local seismographs. The noise set off a flood of calls to 911, and even took the system offline in one area as anxious residents wondered why their windows had shaken. The occupants of the Cessna, a man and woman, met Secret Service on the ground and said they had seen the jets.
The float plane had departed Lake Chelan and flew between Seattle and the mountains to a landing on Lake Washington at Kenmore, where it was met by Secret Service agents. The event began at about 1:38 in the afternoon when the fighters were scrambled. The National Guard jets were given clearance to depart from PDX with an immediate right turn (normal departure follows a different route for noise abatement) and engage afterburners for the intercept. The FAA is investigating and will decide what if any penalties are levied on the pilot of the Cessna.