14 CFR 243.7: Information collection requirements.

(a) For covered flight segments, each covered airline shall:

(1) Collect, or cause to be collected, the full name for each passenger who is a U.S. citizen. U.S.-citizen passengers for whom this information is not obtained shall not be boarded;

(2) Solicit, or cause to be solicited, a name and telephone number of a contact from each passenger who is a U.S. citizen; and

(3) Maintain a record of the information collected pursuant to this section.

(b) The covered airline operating the flight segment shall be responsible for ensuring compliance with paragraph (a) of this section.