Earlier this week, reports of ongoing investigations into a mysterious sonic boom over northern Alabama piqued the interest of astronomers, aviation enthusiasts, and of course, UFO hunters; but Alabama isn’t the only state embroiled in an airborne mystery in recent weeks.  An unidentified and seemingly stealth aircraft was seen by multiple witnesses flying over America’s West Coast last month, and officials still don’t have any idea what it was.

On October 25th, air traffic controllers started addressing the possibility of an unknown aircraft flying somewhere between Portland and Seattle with commercial pilots in the area.  The air traffic controllers were unable to track the aircraft on radar, but had received multiple reports of its presence; further, it was not operating with an activated traffic collision avoidance system (TCAS) transponder, meaning it could potentially pose a threat to the heavily trafficked corridor of airspace.

Numerous pilots confirmed the presence of the aircraft visually, with one getting as close as four miles from it, but could offer little information as to the type of the craft or its origin.  The aircraft did not respond to communications efforts, nor did it display any aggressive behavior toward nearby planes, but the mystery surrounding it created enough concern that the Oregon Air National Guard scrambled F-15 fighters from the Portland International Airport to intercept.  Surprisingly, despite multiple civilian and commercial pilots confirming the craft’s presence and location, it had disappeared before the fighter jets arrived.

With the mysterious aircraft gone, only sparse details remained.  It seemed to have been flying on a northerly course when it was first spotted near Crater Lake, Oregon, at an elevation of between 35,000 and 40,000 feet.  Pilot observations suggest it was flying at a ground speed of around 425 miles per hour (370 knots) and was large enough to be visible to the naked eye at distances as far away as twenty miles, while being small enough to offer little in the way of distinguishing features at a distance of only four.