14 CFR 302.204 - Responsive documents.
(a) Any person may file an answer in support of or in opposition to any application. Answers shall set forth the basis for the position taken, including any economic data or other facts relied on. Except as otherwise provided in § 302.212(d), answers shall be filed within twenty one (21) days of the original or amended application and shall be served in accordance with § 302.203.
(b) Replies to answers shall be filed within fourteen (14) days after the filing of the answer.
(c) Persons having common interests shall, to the extent practicable, arrange for the joint preparation of pleadings.