The Federal Aviation Regulations, or FARs, are rules prescribed by the Federal Aviation Administration (FAA) governing all aviation activities in the United States. The FARs are part of Title 14 of the Code of Federal Regulations (CFR). A wide variety of activities are regulated, such as aircraft design and maintenance, typical airline flights, pilot training activities, hot-air ballooning, lighter-than-air aircraft, man-made structure heights, obstruction lighting and marking, and even model rocket launches, model aircraft operation, sUAS & Drone operation, and kite flying. The rules are designed to promote safe aviation, protecting pilots, flight attendants, passengers and the general public from unnecessary risk. Since 1958, these rules have typically been referred to as "FARs", short for Federal Aviation Regulations. However, another set of regulations (Title 48) is titled "Federal Acquisitions Regulations", and this has led to confusion with the use of the acronym "FAR". Therefore, the FAA began to refer to specific regulations by the term "14 CFR part XX".
The FARs are organized into sections, called parts due to their organization within the CFR. Each part deals with a specific type of activity. For example, 14 CFR Part 141 contains rules for pilot training schools. The sections most relevant to aircraft pilots and AMTs (Aviation Maintenance Technicians) are listed below. Many of the FARs are designed to regulate certification of pilots, schools, or aircraft rather than the operation of airplanes. Once an airplane design is certified using some parts of these regulations, it is certified regardless of whether the regulations change in the future. For that reason, newer planes are certified using newer versions of the FARs, and in many aspects may be thus considered safer designs.
The FARs are divided into tens of thousands of separate sections, many of which have large numbers of researchers using them on any given day. A few of the regulations particularly interesting to laypersons, relevant to current political issues, or of historical interest are listed below.
Many other FARs depend on definitions, which are found in Part 1.1
Part 23 contains airworthiness standards required for issuance and change of type certificates for airplanes in these categories :
In 2016 the FAA proposed a new system of performance-based airworthiness standards instead of prescriptive design requirements. The familiar weight and propulsion classifications of small airplane regulations would be replaced by performance and risk-based standards for aircraft weighing less than 19,000 pounds and seating 19 or fewer passengers. On August 30, 2017, a revised Part 23 ruling went into effect, changing the aircraft classifications. The new passenger classifications are: Level 1, seating for 0 to 1 passenger; Level 2, 2 to 6; Level 3, 7 to 9; Level 4, 10 to 19. Speed classifications are: low speed, Vc or Vmo equal to or less than 250 knots CAS and equal to or less than Mmo 0.6 Mach; high speed, Vc or Vmo greater than 250 knots CAS and Mmo greater than 0.6 Mach.
Prior to August 30, 2017, Part 23 had a large number of regulations to ensure airworthiness in areas such as structural loads, airframe, performance, stability, controllability, and safety mechanisms, how the seats must be constructed, oxygen and air pressurization systems, fire prevention, escape hatches, flight management procedures, flight control communications, emergency landing procedures, and other limitations, as well as testing of all the systems of the aircraft.
It also determined special aspects of aircraft performance such as stall speed (e.g., for single engine airplanes – not more than 61 knots), rate of climb (not less than 300 ft/min), take-off speed (not less than 1.2 x VS1), and weight of each pilot and passenger (170 lb for airplanes in the normal and commuter categories, and 190 lb for airplanes in the acrobatic and utility categories).
Most of the Federal Aviation Regulations, including Part 23, commenced on February 1, 1965. Prior to that date, airworthiness standards for airplanes in the normal, utility and acrobatic categories were promulgated in Part 3 of the US Civil Air Regulations. Many well-known types of light airplane, like the Cessna 150 and Piper Cherokee are certified to these older standards, even though they remained in production after 1965.
This part contains airworthiness standards for airplanes in the transport category.
Transport category airplanes are either:
A rather important section of this part, is the 121 - climbing guaranteed with one engine out for multi-engine aircraft.
Most of the Federal Aviation Regulations, including Part 25, commenced on February 1, 1965. Prior to that date, airworthiness standards for airplanes in the transport category were promulgated in Part 4b of the US Civil Air Regulations which was in effect by November 1945. Effective August 27, 1957, Special Civil Air Regulation (SR) 422 was the basis for certification of the first turbine-powered transport airplanes, such as the Boeing 707, the Lockheed Electra, and the Fairchild 27. SR 422A became effective July 2, 1958, and was superseded by SR 422B, effective August 29, 1959. Only a few airplanes were certified under SR 422A, such as the Gulfstream I and the CL-44. First generation turbine-powered transport category airplanes such as the DC-8, DC-9, and B-727, were originally certified under SR 422B. SR 422B was recodified with minor changes to 14 CFR part 25, which became effective February 1965.
This part contains airworthiness standards for rotorcraft in the normal category. Rotorcraft up to 7,000 lb Maximum Takeoff Weight and 9 or fewer passengers are type certified in this part.
This part contains airworthiness standards for rotorcraft in the transport category. Rotorcraft with more than 7,000 lb (3,200 kg) maximum takeoff weight and 10 or more passengers are type certified in this part. Rotorcraft with more than 20,000 lb (9,100 kg) maximum takeoff weight must be certified to additional Category A standards defined in this part.
This regulation states that the pilot-in-command is the party directly responsible for, and is the final authority as to, an aircraft being operated.
Additionally, this regulation states that in an emergency requiring immediate action, the pilot-in-command may deviate from any regulation contained within Part 91 to the extent required to handle the emergency.
The pertinent sections of the FAR (14 CFR Sections 91.137, 91.138, 91.139, 91.141, 91.143, 91.145, 99.7) describe temporary flight restrictions (TFR). A TFR is a geographically-limited, short-term, airspace restriction, typically in the United States. Temporary flight restrictions often encompass major sporting events, natural disaster areas, air shows, space launches, and Presidential movements. Before the September 11, 2001 attacks, most TFRs were in the interest of safety to flying aircraft with occasional small restrictions for Presidential movements. Since 9/11, TFRs have been routinely used to restrict airspace for 30 nautical miles around the President, with a 10-nautical-mile (18.5 km) radius no-fly zone for non-scheduled flights. They are also available to other high-profile figures such as presidential and vice-presidential candidates (though not all do so, as Senator John Kerry, who did not ask for any TFR during the 2004 election).
TFRs are deeply unpopular with pilots in the general aviation sector. Large Presidential TFRs frequently close off not only the airport Air Force One is using but nearby airports as well. Others, including the Transportation Security Administration, argue that they are necessary for national security.
The responsibility for screening requests for TFR and for subsequent granting or denying them, lies with the FAA's Office of System Operations Security.
Section 91.185 of the Federal Aviation Restrictions deals with loss of radio communications while in flight. If a loss of radio communications were to be encountered during VFR conditions, or if VFR conditions are encountered after loss of communication with the ground and other aircraft, the pilot of the aircraft shall continue the flight under VFR and land as soon as practicable. If, however, the failure occurs in IFR conditions and/or the VFR conditions are not forthcoming, the pilot should continue under the following conditions:
For all pilots, there is an important distinction in the parts that address classes of flight. These parts do not distinguish type of aircraft, but rather type of activity done with the aircraft. Regulations for commuter and commercial aviation are far more intensive than those for general aviation, and specific training is required. Hence, flights are often referred to as Part XX operations, to specify which one of the different sets of rules applies in a particular case. Also, flight schools will often designate themselves as Part 61 or Part 141 to distinguish between different levels of training and different study programs they could offer to the students.
Part 61 is certification for all pilots, flight instructors, and ground instructors.
Part 63 is certification for flight crewmembers other than pilots; such as flight engineers and flight navigators.
Part 65 is certification for airmen other than flight crewmembers; such as Air Traffic Control Tower Operators, Aircraft Dispatchers, Mechanics, Repairmen and Parachute Riggers.
Part 91 is general operating rules for all aircraft. General aviation flights are conducted under this part. Part 91, Subpart (K) prescribes operating rules for fractional ownership programs.
Part 107 (FAA sUAS Part 107) specifies regulations to fly under the Small UAS Rule, or small unmanned aircraft systems in the National Airspace System (NAS). Small unmanned aircraft systems (sUAS) are those that weigh less than 55 pounds. 
Part 117 specifies flight and duty-time limitations and rest requirements for flightcrew members.
Part 121 is scheduled air carrier (airliners).
Part 133 is external load (helicopter) operations.
Part 135 is a set of rules with more stringent standards for commuter and on-demand operations.
Part 141 is a more structured method for pilot training, based on FAA syllabus and other standards.
Part 21 is certification procedures for products and parts.
Part 39 are airworthiness directives.
Part 43 is maintenance, preventive maintenance, rebuilding, and alteration.
Part 145 contains the rules a certificated repair station must follow as well as any person who holds, or is required to hold, a repair station certificate issued under this part.
Part 380 applies to Public Charter air transportation of passengers in interstate or foreign air transportation; whether furnished by a certificated commuter or foreign air carrier, or an air taxi operator, that directly engages in the operation of aircraft; or Public Charter operators