All this talk of 'seeing' the aircraft is nonsense.
Try this yourself a few times:
Spot a high flying aircraft. Watch and time it till you no longer see it.
3 minutes is 24 miles, 6 is 48.
How long after you saw it could you count the engines?
As a rule you will first see it closer than the distance that you lose it. At 6 minutes that means about 12 miles.
Then passengers seeing something 55 miles away - no way. If they were looking out at all cloud would obscure the view.