How to get total number of flights scheduled in an chicago airport for a current date .
If you are looking for actual scheduled flights you would use https://flightaware.com/commercial/aeroapi/explorer/#op_Scheduled
If you want arrived in the past 24 hours, you can use https://flightaware.com/commercial/aeroapi/explorer/#op_Arrived
Let me know more about what you are trying to accomplish and I can see if there is any better calls to make.