Originally Posted by
fumje
Particularly relevant, I have seen people stuck in CBP still 20 minutes before their flight departure who were not permitted to cut the line (they were pleading with staff), and seemingly they missed their flight.
IME UA flights tend to keep their door open past 30 mins (and even past 15 mins) at CBP pre-clearance airports if there's a huge mess and a significant amount of checked-in pax are still missing. They subsequently try to catch up with the lost time en-route (easier if coming from DUB than Y**). Makes sense as most pax would have been CBP processed by the time all the bags would have been offloaded, assuming PPBM still applies on pre-cleared INTL flights.