Sorry. I call BS on this one too. I don't have access to original articles in Portuguese with more information but with the limited information presented in English-language articles, the odds of this "event" being a drone are highly unlikely, and even if it was actually a drone, an extreme overreaction by the air traffic controllers. From the article:
"Operations at Porto airport were put on hold for 40 minutes yesterday afternoon after an aircraft saw a drone flying 5,500 feet from the ground."
(
Drone halts flights at Porto Airport)
Drone was forced to stop Porto Airport in 40 minutes – Observer
Why the airport would halt operations (and it never says the sighting was confirmed) for 40 minutes after a pilot reported a drone over 1 mile high in the air is beyond me. Assuming it actually was a drone, any aircraft spotting a drone at that height would have been a significant distance from the airfield itself. Halting operations (especially takeoffs
and landings) was an extreme overreaction to a singular sighting of a drone (even if in a flightpath) several miles from the runway. (e.g. ca.15 nm on approach). And honestly, I doubt a drone was flying at that height (though it's not impossible) and if it was, it certainly wasn't flying at that altitude for more than a few minutes.