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.

The mystery craft could be any number of a litany of possibilities.  While some are eager to characterize the event as an interaction with an alien space ship, that remains the least likely of them all.  The aircraft appeared to behave much like a traditional airplane in terms of course corrections, trajectory, and speed, whereas most unsolvable UFO reports are usually characterized by behavior modern aircraft are not capable of recreating.  However, just about all of the more likely possibilities have issues as well.

Some believe it was likely an unregistered aircraft being used to mule drugs into Canada – though its stealth characteristics make that an unlikely explanation.  Further, because of the massive amount of border territory between the United States and Canada in that region, smuggling drugs in a four-wheel drive vehicle would be significantly easier and more cost-effective.

If it was an experimental drone, it’s possible that the pilot, located elsewhere, was unable to hear the repeated attempts at communication with the aircraft.  Boeing, who is said to be working on an entry for the Navy’s new MQ-25 Stingray drone competition, does have plants in Washington State, and their entry likely has some stealth capability.  However, most such tests are conducted over open territory like Nevada, and likely wouldn’t have been done without notifying local military assets, like the Air National Guard.

Similarly, an experimental new military aircraft could be responsible, but that still begs the question, if the mysterious aircraft was a new form of drone of military plane, why fly it through a heavily trafficked region of airspace during daylight hours, all but guaranteeing a number of pilots would see it?