US definition of "ultralight" Regulation of ultralight aircraft in the United States is covered by the Code of Federal Regulations Title 14 (Federal Aviation Regulations) Part 103 or 14 CFR Part 103, which defines an "ultralight" as a vehicle that:

• Is used or intended to be used for manned operation in the air by a single occupant;
• Is used or intended to be used for recreation or sport purposes only;
• Does not have any U.S. or foreign airworthiness certificate; and
• If unpowered, weighs less than 155 pounds; or
• If powered:
  1. Weighs less than 254 pounds (115 kg) empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation;
  2. Has a fuel capacity not exceeding 5 U.S. gallons (19 L);
  3. Is not capable of more than 55 knots (102 km/h; 63 mph) calibrated airspeed at full power in level flight; and
  4. Has a power-off stall speed which does not exceed 24 knots (45 km/h; 28 mph) calibrated airspeed.

Certification

• Notwithstanding any other section pertaining to certification of aircraft or their parts or equipment, ultralight vehicles and their component parts and equipment are not required to meet the airworthiness certification standards specified for aircraft or to have certificates of airworthiness.
• Notwithstanding any other section pertaining to airman certification, operators of ultralight vehicles are not required to meet any aeronautical knowledge, age, or experience requirements to operate those vehicles or to have airman or medical certificates.
• Notwithstanding any other section pertaining to registration and marking of aircraft, ultralight vehicles are not required to be registered or to bear markings of any type.

Operations

• No person may operate an ultralight vehicle except between the hours of sunrise and sunset.
• Notwithstanding paragraph (a) of this section, ultralight vehicles may be operated during the twilight periods 30 minutes before official sunrise and 30 minutes after official sunset or, in Alaska, during the period of civil twilight as defined in the Air Almanac, if:
  1. The vehicle is equipped with an operating anticollision light visible for at least 3 statute miles; and
  2. All operations are conducted in uncontrolled airspace.

No person may operate an ultralight vehicle over any congested area of a city, town, or settlement, or over any open air assembly of persons. Weight allowances can be made for two-seat trainers, amphibious landing gear, and ballistic parachute systems. In the United States no license or training is required by law for ultralights, but training is highly advisable.

Exceptions

Although the actual rule does not include explicit exception regarding speed, there are cases where excess speeds do not apply to unconventional flight technology, such as helicopter. Helicopters such as Mosquito take advantage of such exception.