I posted this question generally in the major section under a different topic but was hoping to hear from some united guys on the topic. I am an offline guy who will be buying a ZED for an international United flight. I only have the option to purchase a ticket/list for the economy cabin. Hypothetically if economy is full but there are business seats available does that mean I get left behind due to my economy zed or will I be able to occupy a business seat? Appreciate the responses.