Something can be 'unexplained' simply because there is no explanation, based on the science we have.
For some, that means making a leap into the notion that 'unexplained' is the same as 'alien' which clearly it is not.
One pilot also said the magic word 'spinning' which speaks to the subconscious cliché that aliens must come in saucers that rotate.
As a more measured approach, I would be happy to believe that alien species move among us as I type - they have no physical form, so they don't need 'saucers' to fly in - they are simply energy, and they regard us in the way we regard weeds in the garden.
They have no need to 'make contact' because nothing we can offer can possibly be of the remotest interest to them.