We used to be able to fill in this form on the plane but now travellers to the United States will be required to fill out the Electronic System for Travel Authorization online, before they travel.
Before attempting to register under the Electronic System for Travel Authorization (ESTA), it is advisable to first check your eligibility to travel under the Visa Waiver Program.
Visa Waiver Program travellers should also be aware that unauthorised third-parties have established Web sites, which charge visitors seeking to travel to the United States under the VWP, for information about ESTA and for submitting ESTA applications on behalf of the traveller.
These Web sites are not endorsed by, or affiliated in any way with, the United States government. The U.S. government does not charge a fee for ESTA.
You can submit your application for free at ESTA.