The UK Passenger Locator Form is an important required travel document which all international travelers must fill out prior to departure. The purpose of this document is to restrict the spread of the deadly CO VID-19 influenza virus. If you plan to fly into the UK, you will want to be prepared with this form at the time of check-in. This form can be filled out in several different forms; however, the most popular is the UK Passenger Locator form.