You may call 909-544-5470, 24 hours a day. Please provide the time the aircraft flew over, the direction the aircraft was headed, and if possible, the type of aircraft and airline (or color scheme).
The airport's noise program is discussed on this website in the section entitled "Variance" and in the section "Noise Management Program".
During Santa Ana wind conditions (or whenever the winds are from the east), aircraft landing at ONT will land to the east. If the aircraft is arriving from Northern California, the pattern the aircraft flies is north of the airport.
Between the hours of 10 p.m. and 7 a.m., depending on wind condition, aircraft takes off to the east while still landing to the west. This is called contra-flow. The airport does not allow any high power engine maintenance runs between 10 p.m. and 7 a.m.
FAA Air Traffic Control will occasionally instruct the pilot to fly a different route to ensure the aircraft remains a safe distance from other aircraft in the area.