@madjo

That's exactly what the EU is planning to do, with digital facial and fingerprint image capture on entry into the EU and monitoring on departure for all non-EU citizens.

[quote]The US already receives lists of people that are on board the flights to the US, what more could they want[/quote].

This in ineffective for 2 reasons:

1. It's too late to prevent a potential undesirable from boarding and results in diversion of the aircraft to a remote airport with inconvenience and costs for airline and passengers alike.

2. You're only comparing names and limited data with a database that has been proven to be dodgy, regularly flagging 4 year-olds (and Ted Kennedy) as potential terrorists.

With pre-clearance, you're effectively moving the initial immigration process into a non-critical timeframe.

I'd have no problems with it if it gets me out of the airport quickly on arrival

This is 2 parts arrogance/insanity (armed US air marshals, PNR+ data for overflights) and 1 part common sense (online pre-approval).

If the latter's done sensibly (a word which, of course, is frequently oxymoronic when linked with US government policy), it would expedite processing on arrival and flag any potentially undesirables in a timely manner.

They could probably even adopt the Australian government's on-line visa application algorithms - middle-aged airline executives on vacation tend to pose minimal threat levels to the well-being of a country's citizens, something the Aussies have determined in my case every time.

As does US Immigration at Logan airport when I turn up on their doorstep unannounced.....