(a) This subpart prescribes programming and design and construction standards for projects under the Federal-Aid Airport Program to assure the most efficient use of Program funds and to assure that the most important elements of a national system of airports are provided.

(b) Except for the standards made mandatory by § 151.72(a), the standards prescribed in this subpart that apply to any particular project are those in effect on the date the sponsor accepts the Administrator's offer under § 151.29(c). The standards of § 151.72(a) applicable to a project are those in effect on the date written on the notification of tentative allocation of funds (§ 151.21(b)). Standards that become effective after that date may be applied to the project by agreement between the sponsor and the Administrator.