Based on some recent threads, there seem to be some misunderstandings between exemptions and waivers. Let me see if I can help... Exemption: Simply put, an exemption is a type of rulemaking that is granted to a person or entity in order to relieve them from a regulation when no other means to deviate from the regulation applies. A petitioner for an exemption must describe the regulation, the reason, and how they'd like relief from the regulation. They must also explain why it is in the public interest, and how granting the exemption would not adversely affect safety, or how they would mitigate risk to provide an equivalent level of safety. As it is an act of rulemaking, a petition is published on the Federal Register for notice and comment if it is novel or unique and would set a precedent. Internally, the FAA manages exemptions through the office of rulemaking and is handled at a "headquarters" level. If the exemption is exemption is granted, the exemption will be issued with certain conditions and limitations. In all cases, the exemption is limited to certain persons or entities for a certain period of time, typically two years maximum, but can be reissued. Waiver: Like Deviations and Authorizations, waivers are specifically referenced in the regulations and are typically issued by the FSDO or local FAA authority. A hint that a regulation is waivable is seeing the words "Unless otherwise authorized by the Administrator". Also, a regulation like § 91.905 may list which regulations are subject to waivers. Certain regulations, like § 91.105 Flight crewmembers at stations, are not subject to waiver, and require an exemption for relief. Waivers also do not require a demonstration of public interest, but do require the applicant to describe the proposed operation and how it will meet an equivalent level of safety. Waivers are quite common. Exemptions are comparatively rare. Exemptions are typically issued when a compelling reason exists that the petitioner cannot comply with the regulation. Because the exemption represents rulemaking, multiple repeated grants of exemption are a good indication that the regulation itself requires amendment. Anyone paying attention to unmanned aircraft operations in the last decade has probably noticed that. Because of the level of internal consideration and coordination, exemptions generally take significantly more time to process than waivers.
One well known exemption was the one allowing two seat ultralight trainers. It was widely abused, and was eliminated (except for hang gliders and paragliders) with the creation of Sport Pilot.
One relatively common exemption is flying certain two-Pilot Citations single pilot. Back when I had mine, the pilot’s authorization had to be renewed every year, but the airplane’s paperwork was good until the airplane was sold.
