I need help to identify an API that can give us a count of passengers booked on a flight. Input is greatly appreciated. Thnx.
There are sabre web services that can provide that information, but which service you use depends if you're within the flight operational window or not. If the flight is initialized and within the operational window (which is normally 3 - 5 days before flight departure) you can use the ACS (airport control system) services.
If you're before the operational window, then you need to use other services that show the booked passengers on the flight. From memory I think TripReportsRQ is a web service that can provide that information.
Also there's always the SabreCommandLLSRQ service that will let you issue native sabre commands to obtain this information.