Private jets and foreign customs

I was watching The Hsitory Channels special on private jets this week and had a few questions:

If you own a private jet and fly to a foreign country and land at a private airport or runway, do you have to go through customs?

Are even allowed to land at a private strip?

Yes, you must clear customs.

Every country has designated “Ports of Entry”. These are the only places where you can enter the country (legally). These are not limited to the biggest airports - I’ve cleared customs in Tulsa, OK after departing from Iceland. But the airport must be large enough to justify a Customs contingent.

I don’t know of any private airstrip that also is designated as a Port of Entry.

There is also something called a “Permit to Proceed” that you can get under unusual circumstances. Let’s say your planned Port of Entry (JFK) was socked in with weather and after you burned through your holding fuel you decide to divert to Utica. You must notify them that you are an international flight. You can refuel but cannot open any doors, which means no one gets on or off the airplane. You can get fuel and continue on to your planned destination. This is how the US system works, and the Customs Service obviously like to avoid the “Permit to Proceed” business, so they have customs agents stashed in the most unlikely places!

Go here to find US Ports of Entry listed by State. There are 317 Ports of Entry in the US.

Hope this helps.