"Operations per Hour"

Perhaps you can explain to me how the “Operations per Hour” chart on the upper left of an Airport Activity page is computed.

When I open an airport page, I see a chart of activity level of the previous 24 hours. It is neatly divided into 24 column segments. I guess I’d expect a bar chart there, but the curves are continuous, showing sometimes as many as three peaks within the same hour.

I’ve tried to relate it to the number of flights in the tables for that hour, but then I can’t explain to myself how you get the chart dips within an hour, expecting it to be cumulative, with a dip when the next hour starts and another build-up begins.

I’ve more or less decided you use a sliding time window of unknown (to me) duration to tally the number of operations and then extrapolate the count to an hourly rate.

I could be way off in my thinking. Could you explain it better?

Every few minutes we count the number of operations in the last hour and plot that value. With busy airport it comes out as a nice smooth curve, for rarely visited airports it can appear blocky.