Um I guess planes at first. My dgd when we first moved to our complex she was 3 almost 4.
We are in the flight path of our airport.
We are also in the flight path of fighter jets doing maneuvers from Langley.
You can always tell them apart from regular planes because they will shake the apartment building as well as loud.
My dgd freaked out at first and now she has gotten used to them and apartment will shake and she will say fighter jet lol