I’ve written extensively and passionately about the US Pre-Clearance Facility in Abu Dhabi.
For those of you that haven’t seen my rants on the situation, see here:
— Abu Dhabi Airport United States Immigration Pre-Clearance Facility
— Dubai Airport US Pre-Clearance Facility Coming?
— Etihad’s Abu Dhabi Pre-Clearance Is Still A Disaster
Basically for select US-bound flights, Etihad offers a facility whereby you clear US customs and immigration prior to boarding your flight. This is a model that works quite well in some other countries, like Canada and Ireland, but works horribly in Abu Dhabi. It has literally been consistently delaying US bound flight by hours. Hours.