Unlike almost every other country in the world, the US insists on a full immigration check even for travellers who simply intend to re-board their plane to continue onwards to a foreign destination. Air New Zealand, which flies daily from Heathrow via Los Angeles to Auckland, says there are currently strict requirements for travellers in transit at LAX. Through passengers to Auckland on flight NZ1 or Heathrow on NZ2 must apply in advance for an ESTA (online visa) even though they have no intention of staying in the US. They also have to undergo screening by the Transportation Security Admin

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