Triggering Emails Based on Field Status

OK great, your setup sounds correct now.

When you have a report link field, the Field Properties setup of the field takes care of making sure that only passengers on that flight end up on that embedded report. 

The report name that shows on the form properties might currently be called "Embedded for Flights".  I personally never allow that name to remain because the system auto generates so many of those "embedded for " reports that you can't tell which are actually in use.  So I locate that report in the report list or a better navigation technique is to go into form properties and click the blue link on the panel beside the report link field  called "Change settings" and edit the report to called it "Used on Flights (ie name of Parent table) "   and then you can select your columns for the report, its sort and to finally answer your question, the filters. 

So just filter that embedded report to only include Approved Passengers.