I thought some airports shut down for several hours every night. I'm sitting here in a hotel next to BUF ready to head over there at 4:30 when they officially open so I can stand by for a 6:30 flight. But between 3 and 4 AM I heard at least three planes land and one take off. Could they all be cargo planes (fedex and the like)? Or do airlines move empty planes occasionally? I would just assume they're not unloading pax at this hour.