Any interested person may, within not more than ten days after the filing of an application for review, serve and file with the Department an answer in opposition to, or in support of, such applications. Such answer shall set forth the economic data and other facts upon which it is based.

An answer of the Postmaster General or U.S. Postal Service shall contain the following particular information, where applicable:

The Postal Service's critical time frame for the movement of the mail in question together with a detailed explanation of the operational factors which support that estimate;

The alternate air and surface services (including air taxi service) available in the market in question together with a statement of the costs of using such alternate services and, where appropriate, an explanation of why such services are unacceptable;

An estimate of the average amount and expected actual density of mail which will be tendered to the carrier if the order in question is upheld;

An estimate of the amount and type of containers which will be tendered to the carrier if the order in question is upheld;

The volume (including density of mail, amount and types of containers) of mail historically carried on the flight or flights in question;

An estimate of the volume (including density of mail, amount and types of containers) of mail historically carried on the flight or flights in question which could be accommodated on other flights serving the market without significant impairment of service under the mail delivery time standards of the Postal Service, together with an explanation of how that estimate was computed; and

An estimate of the impact of the flight or flights in question on mail delivery time standards of the Postal Service, together with an explanation of how that estimate was computed.