My mother had a strange sighting late at night in Western NY

I woke up this morning to a text from my mother that she couldn't sleep. She looked outside because she heard a noise. She claims it sounded like an airplane but it was unusually low, unusually slow, and was on her view for 10 or so minutes. She lives in my childhood home which is near Niagara Falls International Airport so seeing aircraft of all sorts is nothing new to us. Along with the other unusualities (is this a word? Not sure.), she stated it was heading AWAY from the airport. This just seemed strange to me so I wanted to report it. She has seem this exact same phenomenon once more when I was probably 11 or 12 (I'm 23 now). I'm very aware this may have been an airplane but I figured it wouldn't hurt to report it. Email is best form of contact.